MySQL condition query if case usage

Where Condition Query

The code is as follows

SELECT * FROM news where DATE (adddate) between

' 2011-04-20 '-INTERVAL 5 day and ' 2011-04-20 ' + INTERVAL 5 day

SELECT * FROM news where DATE (adddate) in (' 2011-04-20 ', ' 2011-04-15 ', ' 2011-04-25 ')

Use of an IF condition statement

Use of the MySQL conditional judgment statement if: First, determine if there exists a specified value exists in the database, the modification does not exist to add.

I'll use it here. The IF statement of the MySQL stored procedure

The code is as follows

DROP PROCEDURE IF EXISTS procedure name;

CREATE PROCEDURE Procedure Name (

In Truename VARCHAR (100),

In Phone VARCHAR (100),

In Qqmsn VARCHAR (100),

In Mail VARCHAR (100),

In Mac VARCHAR (100),

In Heartip VARCHAR (100)

)

Not deterministic

SQL Security Definer

COMMENT '

BEGIN

SELECT count (id) into @maccount the From ' table name ' where ' table name '. Mac=mac; --Is this record present

if (@maccount >0) THEN

Update ' table name ' Set ' Truename ' =truename, ' phone ' =phone, ' qqmsn ' =qqmsn, ' mail ' =mail, ' mac ' =mac,

' Heart ' = ' heart ' +1, ' Heartip ' =heartip, ' heartdatetime ' =current_timestamp WHERE table

Name. Mac=mac;

ELSE

Insert INTO ' table name ' (' Truename ', ' phone ', ' qqmsn ', ' Mail ', ' mac ', ' Heartip ', ' Heartdatetime ') VALUES (TRUENAME,PHONE,QQMSN,

Mail,mac,heartip,current_timestamp);

End IF;

End

Case Condition Statement

The code is as follows

Select substr (t1.area_id, 1, 1) type,

SUBSTR (t1.area_id, 2) ID,

Case substr (t1.area_id, 1, 1)

When ' C ' then

(Select T2.country

From Countnumber.dbtable_countryid T2

where t2.id = substr (t1.area_id, 2))

Else

(SELECT DISTINCT t3.province

from Countnumber.dbtable_provinceid T3

where t3.id = substr (t1.area_id, 2))

End Name

From T_ad_area T1

In the return result of the first scenario, Value=compare-value. The return result of the second scheme is the true result of the first. If there is no matching result value, the result is returned, and if there is no else part, the return value is NULL.

The code is as follows

mysql> SELECT Case 1 when 1 THEN ' one '

-> when 2 THEN ' two ' ELSE ' more ' end;

-> ' One '

Mysql> SELECT case is 1>0 THEN ' true ' ELSE ' false ' end;

-> ' true '

mysql> SELECT case BINARY ' B '

-> when ' a ' THEN 1 when ' B ' THEN 2 end;

-> NULL