Question

我有MySQL数据库的表结构，如下所示：

表格数据：

Ref  | Var | 3SAa combined % | 3SAa combined of | 3SAa Forward of |3SAa Forward % | 3SAa reverse % | 3SAa Forward of|
---------------------------------------------------------------------------------------------------------------------
AL23    TT   0.00              38.78              48.39             100.0            12.01             85.3

我想要的输出如下：

ID   | Ref  |Var |a combined % | a combined of | a Forward of |a Forward % | a reverse % | a Forward of|
--------------------------------------------------------------------------------------------------------
3SA   AL23    TT    0.00              38.78         48.39         100.0        12.01             85.3

我想知道是否有任何方式可以使用MySQL。最大的问题是，我从未找到任何子串函数来截断列名。

Answer 1

您可以在数据库上测试我的查询。您只需要设置前两个变量。 Tablename和包含字符串的行号。

self.b1

<强>测试

 SET @table_name = 'mytab';
 SET @col_id = 3;

 SELECT DATABASE() INTO @dbname;

 SELECT SUBSTRING_INDEX(COLUMN_NAME,' ' , 1)  INTO @id_name
 FROM information_schema.columns
  WHERE table_schema = @dbname 
   AND TABLE_NAME = @table_name
   AND ORDINAL_POSITION = @col_id;

 SELECT CONCAT('SELECT \'', @id_name, '\' AS Id, ' , GROUP_CONCAT(
     CONCAT( '`',COLUMN_NAME,'`')
     , ' AS `', REPLACE(COLUMN_NAME,CONCAT(@id_name,' ') , '')
     ,'`\n' ), ' FROM ', @table_name) INTO @sql
  FROM information_schema.columns
  WHERE table_schema = @dbname 
   AND TABLE_NAME = @table_name
  ORDER BY ORDINAL_POSITION; 

PREPARE stmt FROM @sql;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;

请告诉我它是否适合您

MySQL Pivot表子串列名

1 个答案: