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Monday, 13 January 2014

MySQL Functions - MySQL tutorial for beginners

MySQL Functions -  MySQL tutorial for beginners

Following are functions which is most command used in mysql

Least: Return Least value amont all
SELECT LEAST(4,3,8,-1,5);

Greatest: Return greatest value amont all
SELECT GREATEST(4,3,8,-1,5);

Interval(): takes a comparison value as its first argument. The remaining arguments should be a set of values in sorted order. INTERVAL() compares the first argument to the others and returns a value to indicate how many of them are less than or equal to it.
SELECT INTERVAL(2,1,2,3,4);

BETWEEN: The BETWEEN operator takes the two endpoint values of the range and returns true if a comparison value lies between them and The comparison is inclusive.
SELECT * FROM `products` WHERE id between 1 and 10

ISNULL(0): return true if value is NULL
select ISNULL(1)
Group By: The MySQL GROUP BY statement is used along with the SQL aggregate functions like SUM to provide means of grouping the result. IN: This is a clause, which can be used along with any MySQL query to specify a condition.

BETWEEN: This is a clause, which can be used along with any MySQL query to specify a condition.

UNION: Use a UNION operation to combine multiple result sets into one.

COUNT:  COUNT aggregate function is used to count the number of rows in a database table.

MAX: The MAX aggregate function allows us to select the highest (maximum) value for a certain column.

MIN: The MIN aggregate function allows us to select the lowest (minimum) value for a certain column.

AVG: The AVG aggregate function selects the average value for certain table column.

SUM: The SUM aggregate function allows selecting the total for a numeric column.

SQRT: This is used to generate a square root of a given number.

RAND: This is used to generate a random number using MySQL command.

CONCAT: This is used to concatenate any string inside any MySQL command.

Switch Case in Mysql
CASE  case_expression
   WHEN when_expression_1 THEN execute_statement1
   WHEN when_expression_2 THEN execute_statement1 
   ELSE execute_statement
END CASE;

Example 1
set @variable='10';
select (case when (@variable = '10') then "Equal to 10" else "Not Equal to 10" end)

Example 2
set @variable=10;
select (case when (@variable <=10) then "Less Than Equal to 10" else "Greater Than 10" end)

Example 3
set @variable=10;
select (case
            when (@variable <10) then "Less Than Equal to 10"
            when (@variable =10) then "Equal to 10"
        else "Greater Than 10" end)




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