Sql Server material 14

Set Operators:

COUNT(expression): Returns the number of items in a group.

            SELECT COUNT(*) FROM EMP

            SELECT COUNT(*) FROM EMP WHERE DEPTNO=20

            SELECT COUNT(COMM) FROM EMP

COUNT_BIG(expression): COUNT_BIG works like the COUNT function. The only difference between the two functions is their return values. COUNT_BIG always returns a bigint data type value. COUNT always returns an int data type value.

            SELECT COUNT_BIG(*) FROM EMP

SUM(expression): Returns the sum of all the values. SUM can be used with numeric columns only. Null values are ignored

            SELECT SUM(SAL) FROM EMP

AVG(expression): Returns the average of the values in a group. Null values are ignored.

            SELECT AVG(SAL) FROM EMP

MAX(expression): Returns the maximum value in the expression.

            SELECT MAX(SAL) FROM EMP

MIN(expression): Returns the minimum value in the expression.

            SELECT MIN(SAL) FROM EMP

STDEV(expression): Returns the statistical standard deviation of all values in the specified expression.

            SELECT STDEV(SAL) FROM EMP

VAR(expression): Returns the statistical variance of all values in the specified expression.

            SELECT VAR(SAL) FROM EMP

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