Select
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A SELECT is a SQL command used to query (read) data from one or more database objects, typically from a table, view or materialized view.
Examples[edit]
Select all columns (* = all columns) and all rows from the emp table:
SELECT * FROM emp;
Select the salary column for employee number 7788:
SELECT sal FROM emp WHERE empno = 7788;
Sort rows and return them in order:
SELECT ename, sal FROM emp ORDER BY sal;
Group rows together:
SELECT deptno, COUNT(*) "Employees in department", SUM(sal) "Total salaries for department", AVG(sal) "Avarage salary for department" FROM emp GROUP BY deptno;
SELECT INTO[edit]
PL/SQL and some precompiler languages allow one to select the column values into program variables with the INTO-clause. Typical syntax is:
SELECT ename, sal INTO v_name, v_sal FROM emp WHERE empno = 7788;
Note that this will only work if the query return a single row. If the query returns no rows it will raise a NO_DATA_FOUND exception. If the query returns more than one row, and the variables are not array's, a TOO_MANY_ROWS exception will be raised.
Also see[edit]
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