MySQL 函数 IFNULL 无法与通配符一起正常工作

Question

我有一个 SQL 脚本，在 If Null 语句中使用通配符。 我希望显示所有其他记录，无论字段中是否有空值。

SELECT *  FROM ABC    WHERE   (Value=1 AND        
Prefix like IFNULL(${parameter:X},'%') 
AND        
Base like IFNULL(${parameter:Y},'%')
AND        
Suffix like IFNULL(${parameter:Z},'%')
AND       
Area like IFNULL(${parameter:Ax},'%')       
);

我期望结果应该显示所有值，无论区域字段值是否为空

Answer 1

不要使用like。它将过滤掉数据中的NULL值。只要这样做:

WHERE (NewestVersion = 1 AND        
      (Prefix like ${param:PrefixLookup} or ${param:PrefixLookup} is null) AND
      (Base like ${param:BaseLookup} or ${param:BaseLookup} is null) AND        
      (Suffix like ${param:SuffixLookup} or ${param:SuffixLookup} is null) AND
      (Custom2 like ${param:DRELookup} or ${param:DRELookup} is null) 

如果您有空字符串，则与 NULL 的比较将无济于事。只需使用:

WHERE (NewestVersion = 1 AND        
      (Prefix like ${param:PrefixLookup} or ${param:PrefixLookup} = '') AND
      (Base like ${param:BaseLookup} or ${param:BaseLookup} = '') AND        
      (Suffix like ${param:SuffixLookup} or ${param:SuffixLookup} = '') AND
      (Custom2 like ${param:DRELookup} or ${param:DRELookup} = '')