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What Is a Subquery
What Is a Subquery? - Oracle DBA FAQ - Understanding SQL SELECT Query Statements A subquery is a SELECT statement used as part of the selection criteria of the main SELECT statement. The subquery specified in the WHERE clause will be evaluated repeated on each row of the selection base table. The ou... 2007-04-19, 5218👍, 0💬

How To Use Subqueries with the EXISTS Operator
How To Use Subqueries with the EXISTS Operator? - Oracle DBA FAQ - Understanding SQL SELECT Query Statements A subquery can be used with the EXISTS operator as "EXISTS (subquery)", which returns true if the subquery returns one or more rows. The following statement is a good example of "EXISTS (subq... 2007-04-19, 5194👍, 0💬

How To Use Subqueries with the IN Operator
How To Use Subqueries with the IN Operator? - Oracle DBA FAQ - Understanding SQL SELECT Query Statements A subquery can be used with the IN operator as "expression IN (subquery)". The subquery should return a single column with one or more rows to form a list of values to be used by the IN operation... 2007-04-19, 5121👍, 0💬

How To Count Duplicated Values in a Column
How To Count Duplicated Values in a Column? - Oracle DBA FAQ - Understanding SQL SELECT Query Statements If you have a column with duplicated values, and you want to know what are those duplicated values are and how many duplicates are there for each of those values, you can use the GROUP BY ... HAV... 2007-04-20, 5105👍, 0💬

What Is a SELECT Query Statement
What Is a SELECT Query Statement? - Oracle DBA FAQ - Understanding SQL SELECT Query Statements The SELECT statement is also called the query statement. It is the most frequently used SQL statement in any database application. A SELECT statement allows you to retrieve data from one or more tables, or... 2007-04-21, 5061👍, 0💬

How To Apply Filtering Criteria at Group Level
How To Apply Filtering Criteria at Group Level? - Oracle DBA FAQ - Understanding SQL SELECT Query Statements If you want to return only specific groups from the query, you can apply filtering criteria at the group level by using the HAVING clause inside the GROUP BY clause. The following script give... 2007-04-20, 5036👍, 0💬

Can Group Functions Be Used in the ORDER BY Clause
Can Group Functions Be Used in the ORDER BY Clause? - Oracle DBA FAQ - Understanding SQL SELECT Query Statements If the query output is aggregated as groups, you can sort the groups by using group functions in the ORDER BY clause. The following statement returns how many employees are having the sam... 2007-04-20, 5020👍, 0💬

How To Use Subqueries in the FROM clause
How To Use Subqueries in the FROM clause? - Oracle DBA FAQ - Understanding SQL SELECT Query Statements If you have a query returning many rows of data, and you want to perform another query on those rows, you can put the first query as a subquery in the FROM clause of the second query. The following... 2007-04-19, 4986👍, 0💬

What Are Group Functions
What Are Group Functions? - Oracle DBA FAQ - Understanding SQL SELECT Query Statements Group functions are functions applied to a group of rows. Examples of group functions are: COUNT(*) - Returns the number of rows in the group. MIN(exp) - Returns the minimum value of the expression evaluated on ea... 2007-04-20, 4886👍, 0💬

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.NET C C++ CSS DBA General HTML Java JavaScript JSP JUnit MySQL Networking Oracle Perl Perl PHP PL/SQL RSS Software QA SQL Server Struts Unix Windows XHTML XML