What is in SQL query?

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Best Answer

The SQL SELECT statement returns a result set of records from one or more tables.

A SELECT statement retrieves zero or more rows from one or more database tables or database views.

ORDER BY specifies an order in which to return the rows.

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What is SQL query example?

An SQL SELECT statement retrieves records from a database table according to clauses (for example, FROM and WHERE ) that specify criteria. The syntax is: SELECT column1, column2 FROM table1, table2 WHERE column2='value';

How write a join query in SQL?

Different types of JOINs (INNER) JOIN: Select records that have matching values in both tables. LEFT (OUTER) JOIN: Select records from the first (left-most) table with matching right table records. RIGHT (OUTER) JOIN: Select records from the second (right-most) table with matching left table records.

What are the types of SQL queries?

Types Of SQL Statements With Examples What is SQL? SQL refers to Structured Query Language, as it is the special purpose domain specific language for querying the data in Relational Database Management System (RDBMS). DDL. In Data Definition Language (DDL), we have three different SQL statements. DCL. TCL.

How to use the SQL In Statement with Subquery - SQL Training Online

Which software is used for SQL queries?

SQL statements are used to perform tasks such as update data on a database, or retrieve data from a database. Some common relational database management systems that use SQL are: Oracle, Sybase, Microsoft SQL Server, Access, Ingres, etc.

How do you modify a SQL query?

Select the “SQL Query (input)” tab and click on the “Edit SQL” button. “Edit SQL Statement” dialog will appear. Type a new query definition or modify the existing query and click “OK”.

What is the purpose of order by in an SQL query?

The SQL ORDER BY clause is used to sort the data in ascending or descending order, based on one or more columns. Some databases sort the query results in an ascending order by default.

How do you find the average in SQL query?

SQL SELECT COUNT, SUM, AVG SELECT COUNT returns a count of the number of data values. SELECT SUM returns the sum of the data values. SELECT AVG returns the average of the data values.

What is rollback in SQL?

In SQL, ROLLBACK is a command that causes all data changes since the last BEGIN WORK , or START TRANSACTION to be discarded by the relational database management systems (RDBMS), so that the state of the data is "rolled back" to the way it was before those changes were made.

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What is like in SQL?

The SQL LIKE clause is used to compare a value to similar values using wildcard operators. There are two wildcards used in conjunction with the LIKE operator. The percent sign represents zero, one or multiple characters. The underscore represents a single number or character.

What is Max in SQL?

The aggregate function SQL MAX() is used to find the maximum value or highest value of a certain column or expression. This function is useful to determine the largest of all selected values of a column. Syntax: MAX ([ALL | DISTINCT] expression )

What is Count * in SQL?

What is the COUNT Function in SQL? The SQL COUNT function returns the number of columns in a table fulfilling the criteria indicated in the WHERE clause. It sets the quantity of lines or non-NULL column values.

What is Row_number () in SQL?

ROW_NUMBER. ROW_NUMBER() is a ranking function that numbers the rows within the ordered partition of values defined by its OVER clause. Ranking functions are a subset of window functions.

What is stuff in SQL?

Description. In SQL Server (Transact-SQL), the STUFF function deletes a sequence of characters from a source string and then inserts another sequence of characters into the source string, starting at a specified position.

Best Way to Write Basic SQL Queries

What is the use of in SQL?

The SQL IN condition (sometimes called the IN operator) allows you to easily test if an expression matches any value in a list of values. It is used to help reduce the need for multiple OR conditions in a SELECT, INSERT, UPDATE, or DELETE statement.

What is order by clause in SQL?

Advertisements. The SQL ORDER BY clause is used to sort the data in ascending or descending order, based on one or more columns. Some databases sort the query results in an ascending order by default.

What is group by rollup in SQL?

The ROLLUP is an extension of the GROUP BY clause. The ROLLUP option allows you to include extra rows that represent the subtotals, which are commonly referred to as super-aggregate rows, along with the grand total row. By using the ROLLUP option, you can use a single query to generate multiple grouping sets.

What is where clause in SQL?

A WHERE clause in SQL specifies that a SQL Data Manipulation Language (DML) statement should only affect rows that meet specified criteria. In brief SQL WHERE clause is used to extract only those results from a SQL statement, such as: SELECT, INSERT, UPDATE, or DELETE statement.

What is Group By clause in SQL?

Group by clause is used to group the results of a SELECT query based on one or more columns. It is also used with SQL functions to group the result from one or more tables. Syntax for using Group by in a statement. SELECT column_name, function(column_name) FROM table_name WHERE condition GROUP BY column_name.

What is having clause in SQL?

A HAVING clause in SQL specifies that an SQL SELECT statement should only return rows where aggregate values meet the specified conditions. It was added to the SQL language because the WHERE keyword could not be used with aggregate functions.

What is the use of <> in SQL?

The SQL IN condition (sometimes called the IN operator) allows you to easily test if an expression matches any value in a list of values. It is used to help reduce the need for multiple OR conditions in a SELECT, INSERT, UPDATE, or DELETE statement.

Is not condition in SQL?

The SQL NOT condition (sometimes called the NOT Operator) is used to negate a condition in the WHERE clause of a SELECT, INSERT, UPDATE, or DELETE statement.

What are views in SQL?

In SQL, a view is a virtual table based on the result-set of an SQL statement. The fields in a view are fields from one or more real tables in the database. You can add SQL functions, WHERE, and JOIN statements to a view and present the data as if the data were coming from one single table.

What is SQL operator?

An operator is a reserved word or a character used primarily in an SQL statement's WHERE clause to perform operation(s), such as comparisons and arithmetic operations. These Operators are used to specify conditions in an SQL statement and to serve as conjunctions for multiple conditions in a statement.

What is difference between in and exists in SQL?

EXISTS is much faster than IN , when the sub-query results is very large,the EXISTS operator provides a better performance. IN is faster than EXISTS , when the sub-query results is very small. The Exists keyword evaluates true or false, but IN keyword compare all value in the corresponding sub query column.

What is SQL is SQL a scripting language?

SQL (pronounced "ess-que-el") stands for Structured Query Language. SQL is used to communicate with a database. SQL statements are used to perform tasks such as update data on a database, or retrieve data from a database.

What is SQL clause?

SQL - Having Clause. Advertisements. The HAVING Clause enables you to specify conditions that filter which group results appear in the results. The WHERE clause places conditions on the selected columns, whereas the HAVING clause places conditions on groups created by the GROUP BY clause.

What is Group By clause in SQL with example?

The GROUP BY Statement in SQL is used to arrange identical data into groups with the help of some functions. i.e if a particular column has same values in different rows then it will arrange these rows in a group. GROUP BY clause is used with the SELECT statement.

What is difference between unique and distinct in SQL?

While DISTINCT is ANSI SQL standard, UNIQUE is an Oracle specific statement. Specify DISTINCT or UNIQUE if you want the database to return only one copy of each set of duplicate rows selected. These two keywords are synonymous. Duplicate rows are those with matching values for each expression in the select list.

What is difference between subquery and correlated query?

The main difference between a regular, non-correlated and correlated subquery in SQL is in their working, a regular subquery just run once and return a value or a set of values which is used by outer query, but correlated subquery runs for each row returned by the outer query because the output of the whole query is

What is the default order by in SQL?

The SQL ORDER BY Keyword. The ORDER BY keyword is used to sort the result-set in ascending or descending order. The ORDER BY keyword sorts the records in ascending order by default. To sort the records in descending order, use the DESC keyword.

What is the difference between where and having in SQL?

2) WHERE clause is used for filtering rows and it applies on each and every row, while HAVING clause is used to filter groups in SQL. 3) One syntax level difference between WHERE and HAVING clause is that, former is used before GROUP BY clause, while later is used after GROUP BY clause.

What is the use of commit and rollback in SQL?

Commit, Rollback and Savepoint SQL commands. Transaction Control Language(TCL) commands are used to manage transactions in the database. These are used to manage the changes made to the data in a table by DML statements. It also allows statements to be grouped together into logical transactions.

What is order by and group by in SQL?

The GROUP BY Statement in SQL is used to arrange identical data into groups with the help of some functions. i.e if a particular column has same values in different rows then it will arrange these rows in a group. In the query, GROUP BY clause is placed before ORDER BY clause if used any.

Is Top an aggregate function in SQL?

An aggregate function performs a task in relation to one or more values from a single column and returns a single value. The supported functions are: SUM — returns the sum of the values of a specified column. AVG — returns the average of the values of the specified column.

What is difference between SQL and SQL Server?

1.SQL is a programming language while T-SQL is an extension to SQL. 2.T-SQL is proprietary while SQL is an open format. Yes, SQL = Structured Query Language, a standardized (thanks to ANSI) query language for querying relational databases (such as Microsoft SQL Server, Oracle, Sybase, MySQL, etc.)

What is SQL used for?

SQL is used to communicate with a database. According to ANSI (American National Standards Institute), it is the standard language for relational database management systems. SQL statements are used to perform tasks such as update data on a database, or retrieve data from a database.

What does aggregate mean in SQL?

| Aggregate functions in SQL. In database management an aggregate function is a function where the values of multiple rows are grouped together as input on certain criteria to form a single value of more significant meaning.

What does group by in SQL do?

The GROUP BY Statement in SQL is used to arrange identical data into groups with the help of some functions. i.e if a particular column has same values in different rows then it will arrange these rows in a group. In the query, GROUP BY clause is placed before ORDER BY clause if used any.

Which clause is executed first in SQL?

SELECT Statement Execution Order. In SQL, the first clause that is processed is the FROM clause, while the SELECT clause, which appears first in an SQL query, is processed much later.

What are aggregate functions in SQL?

Aggregate functions in SQL. In database management an aggregate function is a function where the values of multiple rows are grouped together as input on certain criteria to form a single value of more significant meaning.

What does rollup do in SQL?

The ROLLUP operator is used with the GROUP BY clause. It is used to create subtotals and grand totals for a set of columns. The summarized amounts are created based on the columns passed to the ROLLUP operator. The CUBE operators, like the ROLLUP operator produces subtotals and grand totals as well.

What is the order of clauses in SQL?

SQL clauses. The ORDER BY clause is an optional element of a SELECT statement. An ORDER BY clause allows you to specify the order in which rows appear in the ResultSet.

What is commit rollback and savepoint in SQL?

Commit, Rollback and Savepoint SQL commands. Transaction Control Language(TCL) commands are used to manage transactions in the database. These are used to manage the changes made to the data in a table by DML statements. It also allows statements to be grouped together into logical transactions.

What is the difference between unique and distinct in SQL?

While DISTINCT is ANSI SQL standard, UNIQUE is an Oracle specific statement. Specify DISTINCT or UNIQUE if you want the database to return only one copy of each set of duplicate rows selected. These two keywords are synonymous. Duplicate rows are those with matching values for each expression in the select list.

What is the difference between union and distinct in SQL?

2 Answers. The difference between Union and Union all is that UNION ALL will not eliminate duplicate rows, instead it just pulls all rows from all tables fitting your query specifics and combines them into a table. A UNION statement effectively does a SELECT DISTINCT on the results set.

What is the use of == === operators in SQL?

The AND operator allows the existence of multiple conditions in an SQL statement's WHERE clause. The ANY operator is used to compare a value to any applicable value in the list according to the condition.

Why group by is used in SQL?

The GROUP BY clause is a SQL command that is used to group rows that have the same values. The GROUP BY clause is used in the SELECT statement .Optionally it is used in conjunction with aggregate functions to produce summary reports from the database. That's what it does, summarizing data from the database.

Is Max an aggregate function in SQL?

SQL Server MAX() function is an aggregate function that returns the maximum value in a set.

What does count (*) do in SQL?

The SQL COUNT() function returns the number of rows in a table satisfying the criteria specified in the WHERE clause. It sets the number of rows or non NULL column values. Overall, you can use * or ALL or DISTINCT or some expression along with COUNT to COUNT the number of rows w.r.t.

What does limit do in SQL?

Description. The SQL SELECT LIMIT statement is used to retrieve records from one or more tables in a database and limit the number of records returned based on a limit value. TIP: SELECT LIMIT is not supported in all SQL databases.

Which join is faster in SQL?

SQL Server - Which is faster INNER JOIN or LEFT JOIN? You may be interested to know which is faster – the LEFT JOIN or INNER JOIN. Well, in general INNER JOIN will be faster because it only returns the rows matched in all joined tables based on the joined column.

Does count in SQL?

The SQL COUNT() function returns the number of rows in a table satisfying the criteria specified in the WHERE clause. It sets the number of rows or non NULL column values.

Which is faster in or exists in SQL?

The EXISTS clause is much faster than IN when the subquery results is very large. Conversely, the IN clause is faster than EXISTS when the subquery results is very small. Also, the IN clause can't compare anything with NULL values, but the EXISTS clause can compare everything with NULLs.

How does work in SQL?

Having (SQL) A HAVING clause in SQL specifies that an SQL SELECT statement should only return rows where aggregate values meet the specified conditions. It was added to the SQL language because the WHERE keyword could not be used with aggregate functions.

Where exists in SQL Server?

SQL Server EXISTS operator overview. The EXISTS operator is a logical operator that allows you to check whether a subquery returns any row. The EXISTS operator returns TRUE if the subquery returns one or more row. In this syntax, the subquery is a SELECT statement only.

How use any in SQL?

SQL WHERE ANY, ALL Clause ANY and ALL keywords are used with a WHERE or HAVING clause. ANY and ALL operate on subqueries that return multiple values. ANY returns true if any of the subquery values meet the condition. ALL returns true if all of the subquery values meet the condition.

What does an except query return?

SQL - EXCEPT Clause. Advertisements. The SQL EXCEPT clause/operator is used to combine two SELECT statements and returns rows from the first SELECT statement that are not returned by the second SELECT statement. This means EXCEPT returns only rows, which are not available in the second SELECT statement.

What is an aggregate function SQL?

An aggregate function performs a calculation on a set of values, and returns a single value. Except for COUNT , aggregate functions ignore null values. Aggregate functions are often used with the GROUP BY clause of the SELECT statement.

Where not exists in SQL?

The SQL NOT EXISTS Operator will act quite opposite to EXISTS Operator. It is used to restrict the number of rows returned by the SELECT Statement. The NOT EXISTS in SQL Server will check the Subquery for rows existence, and if there are no rows then it will return TRUE, otherwise FALSE.

Can we use Groupby and orderby in same query?

GROUP BY and ORDER BY can be used in the same query and it is NOT required that they be the same column. GROUP BY controls the way the data is organized for sumarization. ORDER BY simply sorts the rows of the result. ORDER BY AVG desc.

Is a relationship SQL?

2. One-Many Relationship (1-M Relationship) The One-to-Many relationship is defined as a relationship between two tables where a row from one table can have multiple matching rows in another table. This relationship can be created using Primary key-Foreign key relationship.

IS NOT NULL SQL?

The IS NOT NULL condition is used in SQL to test for a non-NULL value. It returns TRUE if a non-NULL value is found, otherwise it returns FALSE. It can be used in a SELECT, INSERT, UPDATE, or DELETE statement.

Is SQL software free?

For your information SQL is acronym for Structured Query Language, which is used by many of the DBMS to perform operations on the database. There are proprietary(MS-SQL, Oracle) and free(MySQL, PostgreSQL) DBMS which uses it. SQL server is a licensed software. So you can't get it for free.

What are SQL triggers?

In a DBMS, a trigger is a SQL procedure that initiates an action (i.e., fires an action) when an event (INSERT, DELETE or UPDATE) occurs. Since triggers are event-driven specialized procedures, they are stored in and managed by the DBMS. Each trigger is attached to a single, specified table in the database.

What are SQL functions?

A function is a database object in SQL Server. Basically, it is a set of SQL statements that accept only input parameters, perform actions and return the result. A function can return an only a single value or a table. We can't use a function to Insert, Update, Delete records in the database tables.

What does group by 1 mean in SQL?

It means to group by the first column regardless of what it's called. You can do the same with ORDER BY. In above query GROUP BY 1 refers to the first column in select statement which is account_id .

Is SQL open source?

MySQL (/ˌmaɪˌɛsˌkjuːˈɛl/ "My S-Q-L") is an open-source relational database management system (RDBMS). MySQL is free and open-source software under the terms of the GNU General Public License, and is also available under a variety of proprietary licenses.

What does rollback do SQL?

In SQL, ROLLBACK is a command that causes all data changes since the last BEGIN WORK , or START TRANSACTION to be discarded by the relational database management systems (RDBMS), so that the state of the data is "rolled back" to the way it was before those changes were made.

How does group by work in SQL?

The SQL GROUP BY Statement. The GROUP BY statement group rows that have the same values into summary rows, like "find the number of customers in each country". The GROUP BY statement is often used with aggregate functions (COUNT, MAX, MIN, SUM, AVG) to group the result-set by one or more columns.

How do you find Max in SQL?

To get the maximum value of a numeric column use the MAX() function. SELECT MAX(&lt;numeric column&gt;) FROM &lt;table&gt;; SELECT MAX(&lt;numeric column&gt;) FROM &lt;table&gt; GROUP BY &lt;other column&gt;; To get the minimum value of a numeric column use the MIN() function.

How do I count values in SQL?

SQL SELECT COUNT, SUM, AVG SELECT COUNT returns a count of the number of data values. SELECT SUM returns the sum of the data values. SELECT AVG returns the average of the data values.

How do you join tables in SQL?

Different types of JOINs (INNER) JOIN: Select records that have matching values in both tables. LEFT (OUTER) JOIN: Select records from the first (left-most) table with matching right table records. RIGHT (OUTER) JOIN: Select records from the second (right-most) table with matching left table records.

How do I sort by in SQL?

The ORDER BY statement in sql is used to sort the fetched data in either ascending or descending according to one or more columns. By default ORDER BY sorts the data in ascending order. We can use the keyword DESC to sort the data in descending order and the keyword ASC to sort in ascending order.

Can Delete be rolled back in SQL?

If TRUNCATE is written in Query Editor surrounded by TRANSACTION and if session is closed, it can not be rolled back but DELETE can be rolled back. In case of DELETE, SQL Server removes all the rows from table and records them in Log file in case it is needed to rollback in future. Due to that reason it is slow.

How do I find duplicates in SQL?

SELECT id, COUNT(id) FROM table1 GROUP BY id HAVING COUNT(id)&gt;1; I think this will work properly to search repeated values in a particular column. This should also work, maybe give it try. If you want to find duplicate data (by one or several criterias) and select the actual rows.

Why views are used in SQL?

View can be described as virtual table which derived its data from one or more than one table columns. It is stored in the database. View can be created using tables of same database or different database. It is used to implement the security mechanism in the SQL Server.

Where does group by Go in SQL?

The GROUP BY Statement in SQL is used to arrange identical data into groups with the help of some functions. i.e if a particular column has same values in different rows then it will arrange these rows in a group. Important Points: GROUP BY clause is used with the SELECT statement.

How do you count in SQL?

The SQL COUNT function is an aggregate function that returns the number of rows returned by a query. You can use the COUNT function in the SELECT statement to get the number of employees, the number of employees in each department, the number of employees who hold a specific job, etc. COUNT([ALL. DISTINCT] expression);

Why are views used in SQL?

Views are used for security purposes because they provide encapsulation of the name of the table. Data is in the virtual table, not stored permanently. Views display only selected data. We can also use Sql Join s in the Select statement in deriving the data for the view.

How not exists works in SQL?

The subquery is a SELECT statement. If the subquery returns at least one record in its result set, the EXISTS clause will evaluate to true and the EXISTS condition will be met. If the subquery does not return any records, the EXISTS clause will evaluate to false and the EXISTS condition will not be met.

How do you rank in SQL?

SQL Server supports four ranking functions: ROW_NUMBER: Assigns a sequential number to each row in the result set. RANK: Ranks each row in the result set. DENSE_RANK: Ranks each row in the result set. NTILE: Divides the result set into the number of groups specified as an argument to the function.

How do I use Groupby in SQL?

The GROUP BY clause is a SQL command that is used to group rows that have the same values. The GROUP BY clause is used in the SELECT statement .Optionally it is used in conjunction with aggregate functions to produce summary reports from the database.

What is the difference between group by and order by in SQL?

ORDER BY : It alters the order in which items are returned. GROUP BY : It will aggregate records by the specified columns which allows you to perform aggregation functions on non-grouped columns (such as SUM, COUNT, AVG, etc). The ORDER BY clause's purpose is to sort the query result by specific columns.

What is the difference between orderby and group by in SQL?

SQL allows to organize the data obtained by the query. The point that distinguishes Group By and Order By clause is that Group By clause is used when we want to apply the aggregate function to more than one set of tuples and Order By clause is used when we want to sort the data obtained by the query.

Why SQL Server is used?

SQL is used to communicate with a database. SQL statements are used to perform tasks such as update data on a database, or retrieve data from a database. Some common relational database management systems that use SQL are: Oracle, Sybase, Microsoft SQL Server, Access, Ingres, etc.

What are SQL aggregate functions?

The following are the most commonly used SQL aggregate functions: AVG – calculates the average of a set of values. COUNT – counts rows in a specified table or view. MIN – gets the minimum value in a set of values. MAX – gets the maximum value in a set of values. SUM – calculates the sum of values.

How do you use exists in SQL?

The SQL EXISTS condition is used in combination with a subquery and is considered to be met, if the subquery returns at least one row. It can be used in a SELECT, INSERT, UPDATE, or DELETE statement. The syntax for the EXISTS condition in SQL is: WHERE EXISTS (subquery). The subquery is a SELECT statement.

How do you aggregate data in SQL?

Aggregate functions in SQL COUNT counts how many rows are in a particular column. SUM adds together all the values in a particular column. MIN and MAX return the lowest and highest values in a particular column, respectively. AVG calculates the average of a group of selected values.

Is SQL Server Open Source?

This week, the company announced that SQL Server, its enterprise database platform, will now run on open source operating systems as well as Windows servers. The big catch for open source fans is that SQL Server is not actually becoming open source.

How do you group a query?

If you want to follow along in our database, open the Menu Items Ordered query. Create or open a query you want to use as a totals query. From the Design tab, locate the Show/Hide group, then select the Totals command. A row will be added to the table in the design grid, with all values in that row set to Group By.

How do I group query results?

To use the Count and Group By options in a query: Click Totals in the Show/Hide group on the Ribbon. Totals Command. Click in the Totals row for the field you want to count. From the list of optional Totals functions, select Count. Click Run! to see your results.

What is the language used to build SQL?

To hold this data, a database system is used. SQL (structured query language) is a programming language that enables programmers to work with that data. While an application might be programmed in a language like Python, PHP or Ruby, databases are not configured to understand these.

What is the difference between count 1 and count (*) in SQL?

The difference is simple: COUNT(*) counts the number of rows produced by the query, whereas COUNT(1) counts the number of 1 values. This is because the database can often count rows by accessing an index, which is much faster than accessing a table.

How do you arrange in descending order in SQL?

ORDER BY. The ORDER BY statement in sql is used to sort the fetched data in either ascending or descending according to one or more columns. By default ORDER BY sorts the data in ascending order. We can use the keyword DESC to sort the data in descending order and the keyword ASC to sort in ascending order.

What are the basics of SQL?

SQL is a database computer language designed for the retrieval and management of data in a relational database. SQL stands for Structured Query Language. This tutorial will give you a quick start to SQL. It covers most of the topics required for a basic understanding of SQL and to get a feel of how it works.

What are the basic commands of SQL?

The commands are CREATE, ALTER, DROP, RENAME, and TRUNCATE. Data Manipulation Language (DML) - These SQL commands are used for storing, retrieving, modifying, and deleting data. These Data Manipulation Language commands are: SELECT, INSERT, UPDATE, and DELETE.

Is it hard to learn SQL?

It is not really difficult to learn SQL. SQL is not a programming language, it's a query language. The good news is that most DB engines are compatible with all SQL code. So once you learn SQL it should be similar to work across any relational databases.

Why is SQL better than Excel?

SQL is much faster than Excel. It can take minutes in SQL to do what it takes nearly an hour to do in Excel. Excel can technically handle one million rows, but that's before the pivot tables, multiple tabs, and functions you're probably using. When using SQL, your data is stored separately from your analysis.

How do I count by group in SQL?

GROUP BY returns one records for each group. GROUP BY typically also involves aggregates: COUNT, MAX, SUM, AVG, etc. The general syntax with ORDER BY is: SELECT column-names. FROM table-name. WHERE condition. GROUP BY column-names. ORDER BY column-names.

How does Group By clause work in SQL?

Summary The GROUP BY Clause is used to group rows with same values . The GROUP BY Clause is used together with the SQL SELECT statement. The SELECT statement used in the GROUP BY clause can only be used contain column names, aggregate functions, constants and expressions.