MySQL condition query if case usage detailed

Where Condition Query

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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

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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

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Select substr (t1.area_id, 1, 1) type,        substr (t1.area_id, 2) ID,  & nbsp;     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

The

is value=compare-value in the return result of the first scenario. 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.

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mysql> SELECT Case 1 if 1 THEN ' one '    ->     when 2 THEN ' two ' ELSE ' more ' end;        -> ' one ' mysql> SELECT case 1>0 THEN ' true ' ELSE ' False ' end;        -> ' true ' Mysql> SELECT case BINARY ' B '    ->     when ' a ' THEN 1 while ' B ' THEN 2 end;        -> NULL