Mysql (15) process control _ MySQL

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Mysql (15) process control

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Mysql (1) installation of mysql

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Mysql-related operations (2)

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Mysql operations on data tables (3)

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Mysql (4) Data Table query operations

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Mysql operations (5)

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Mysql (6) string pattern matching

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Mysql (7) in-depth select query

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Mysql Index (8)

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Mysql common functions

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Mysql (10) trigger 1

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Mysql things (11) trigger 2

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Mysql stored procedures

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Mysql (13) usage of variables and conditions

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Mysql usage of those things (14) cursor

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IF statement

SQL code

--- Syntax structure

IF search_condition THEN statement_list

[ELSEIF search_condition THEN statement_list]...

[ELSE statement_list]

END IF

--- Example

If I _staff_id = 2 then

Set @ x1 = @ x1 + d_amount;

Else

Set @ x2 = @ x2 + d_amount;

End if;

CASE Statement

SQL code

--- Syntax format of the CASE statement

CASE case_value

WHEN when_value THEN statement_list

[WHEN when_value THEN statement_list]...

[ELSE statement_list]

END CASE

--- Example of case statement:

Case

When I _staff_id = 2 then

Set @ x1 = @ x1 + d_amount;

Else

Set @ x2 = @ x2 + d_amount;

End case

LOOP statement

SQL code

[Begin_label:] LOOP

Statement_list

End loop [end_label]

--- If you do not add an exit LOOP statement in statement_list, the LOOP statement can be used to implement a simple endless LOOP.

LEAVE statement

SQL code

--- Replace the Terminator with $

Delimiter $

--- Create a stored procedure

Create procedure actor_num ()

BEGIN

Set @ x = 0;

Ins: LOOP

Set @ x = @ x + 1;

IF @ x = 100 THEN

Leave ins;

End if;

Insert into actor (first_name, last_name) VALUES ('test', 222 );

End loop ins;

END;

$

Delimiter;

ITERATE statement

SQL code

-- It must be used in a loop to skip the current loop and directly enter the next loop.

Delimiter $

Create procedure actor_num ()

BEGIN

Set @ x = 0;

Ins: LOOP

Set @ x = @ x + 1;

IF @ x = 100 THEN

Leave ins;

ELSEIF mod (@ x/2, 0) = 0 THEN

Iterate ins;

End if;

Insert into actor (first_name, last_name) VALUES ('test', 222 );

End loop ins;

END;

$

Delimiter;

REPEAT statement

SQL code

-- Conditional loop: exit the loop when conditions are met.

-- Syntax:

[Begin_label:] REPEAT

Statement_list

UNTIL search_condition

End repeat [end_label]

-- Example

REPEAT

FETCH cur_payment INTO I _staff_id, d_amount;

If I _staff_id = 2 then

Set @ x1 = @ x1 + d_amount;

Else

Set @ x2 = @ x2 + d_amount;

End if;

UNTIL 0 end repeat;

WHILE statement

SQL code

--- Syntax structure

[Begin_label:] WHILE search_condition DO

Statement_list

End while [end_label]

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