如何在SQL的where子句中串联多个列？

Question

如果我要搜索一个城市地址，例如“奎松市”，就会有结果。 但是，如果我要搜索“马尼拉大都会奎松市”这样的城市地址和省份，那么应该没有结果。

到目前为止，这是我的SQL查询。

//TABLES
   t1 = street
   t3 = province
   t4 = city
   t5 = village

SELECT t1.*
     , t1.name AS propertyname
     , t2.name AS typeName
     , t3.name AS provName
     , t4.name AS cityName
     , t5.name AS brgyName
     , t6.imgpath_tn AS imgName
FROM proplistings AS t1
     LEFT JOIN proptypes AS t2 ON t2.id = t1.property_type_id
     LEFT JOIN tbl_province AS t3 ON t3.id = t1.prov_id 
     LEFT JOIN tbl_city AS t4 ON t4.id = t1.city_id
     LEFT JOIN tbl_barangay AS t5 ON t5.id = t1.brgy_id
     LEFT JOIN proplistings_images AS t6 ON t6.propid = t1.id
WHERE t1.deleted = 0
     AND t1.announceas = '1'
     AND t6.defaultimg = 1
     AND t6.imgpath != ''
     AND t1.status=1
     AND CONCAT(t1.street,', t5.name,', ', t4.name,', ', t3.name, ',t1.propcode,', ')
         LIKE '%Quezon City, Metro Manila%'
ORDER BY t1.date_added DESC

Answer 1

如果concat并且任何列包含null，则结果为null。 尝试编码为空。

例如

set @a = 'abc';
set @b = null;

select @a,@b,concat(@a,@b),
        concat(ifnull(@a,''),ifnull(@b,''));

+------+------+---------------+-------------------------------------+
| @a   | @b   | concat(@a,@b) | concat(ifnull(@a,''),ifnull(@b,'')) |
+------+------+---------------+-------------------------------------+
| abc  | NULL | NULL          | abc                                 |
+------+------+---------------+-------------------------------------+
1 row in set (0.00 sec)

Answer 2

我发现了2个问题。

我看到您按以下顺序连接： ... + province + city + ...因此，如果Quezon City是城市， Metro Manila是省-级联的结果看起来像： Metro Manila, Quezon City所以您必须使用LIKE '%Metro Manila, Quezon City%'而不是LIKE '%Quezon City, Metro Manila%' 。

另外，您还必须使用IFNULL以避免空值的串联，因为如果CONCAT任何值将为NULL整个结果将为NULL 。

因此，您的WHERE子句应如下所示：

WHERE t1.deleted = 0
     AND t1.announceas = '1'
     AND t6.defaultimg = 1
     AND t6.imgpath != ''
     AND t1.status=1
     AND CONCAT(IFNULL(CONCAT(t1.street,', '), ''),
                IFNULL(CONCAT(t1.propcode,', '), ''), 
                IFNULL(CONCAT(t3.name,', '), ''), 
                IFNULL(CONCAT(t4.name,', '), ''), 
                IFNULL(CONCAT(t5.name,', '), '')
         )
         LIKE REPLACE(REPLACE('%Metro Manila, Quezon City%',' ','%'),',','%')

或者您可以使用动态SQL，例如：

DECLARE @SearchStr VARCHAR(1000)
DECLARE @Query VARCHAR(1000)

SET @SearchStr = 'Metro Mangila, Quezon City'

SET @Query = 'SELECT t1.*
                     , t1.name AS propertyname
                     , t2.name AS typeName
                     , t3.name AS provName
                     , t4.name AS cityName
                     , t5.name AS brgyName
                     , t6.imgpath_tn AS imgName
                FROM proplistings AS t1
                     LEFT JOIN proptypes AS t2 ON t2.id = t1.property_type_id
                     LEFT JOIN tbl_province AS t3 ON t3.id = t1.prov_id 
                     LEFT JOIN tbl_city AS t4 ON t4.id = t1.city_id
                     LEFT JOIN tbl_barangay AS t5 ON t5.id = t1.brgy_id
                     LEFT JOIN proplistings_images AS t6 ON t6.propid = t1.id
                WHERE t1.deleted = 0
                     AND t1.announceas = ''1''
                     AND t6.defaultimg = 1
                     AND t6.imgpath != ''''
                     AND t1.status=1
                     AND (
                     CONCAT(IFNULL(CONCAT(t1.street,'', ''), ''''),
                            IFNULL(CONCAT(t1.propcode,'', ''), ''''), 
                            IFNULL(CONCAT(t3.name,'', ''), ''''), 
                            IFNULL(CONCAT(t4.name,'', ''), ''''), 
                            IFNULL(CONCAT(t5.name,'', ''), '''')
                     ) LIKE ''%' + REPLACE(@SearchStr, ' ', '%'' 
                     OR 
                     CONCAT(IFNULL(CONCAT(t1.street,'', ''), ''''),
                            IFNULL(CONCAT(t1.propcode,'', ''), ''''), 
                            IFNULL(CONCAT(t3.name,'', ''), ''''), 
                            IFNULL(CONCAT(t4.name,'', ''), ''''), 
                            IFNULL(CONCAT(t5.name,'', ''), '''')
                     )  LIKE ''%' + '%'')'
EXEC(@Query)