Question

我是MySQL的新手。现在，我有40张桌子。它们的一部分包含一个名为“ case_id”（字符）的字段。我想查找哪些表具有“ case_id”列，但没有case_id =“ 123”。

我只选择所有具有“ case_id”列的表，但是我不知道如何从中查找所需的表。

您有什么建议吗？非常感谢！

select DISTINCT TABLE_NAME as test_table from INFORMATION_SCHEMA.COLUMNS where COLUMN_NAME IN ("case_id") and TABLE_SCHEMA="test_db";

例如，

表A的记录为“ case_id” =“ 123”。因此，它不会被打印。表B不包含“ case_id”列，也不会打印。表C具有“ case_id”，但没有“ case_id” =“ 123”的记录，将打印名称“ Table C”。

编辑＃2

只需根据@abk的答案更新我的代码。我只是更改了方案的名称。

CREATE DEFINER=`root`@`localhost` PROCEDURE `MISS_CASE_CHECK`()
BEGIN
    DECLARE Table_name TEXT;
    DECLARE done INT DEFAULT 0;
    DECLARE str  LONGTEXT;
    DECLARE my_cursor CURSOR FOR
    SELECT DISTINCT TABLE_NAME
    From INFORMATION_SCHEMA.COLUMNS
    WHERE COLUMN_NAME IN ("case_id") and TABLE_SCHEMA="wes_bk";

    DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = 1;

    OPEN my_cursor;
   SET str = '';      
    WHILE done = 0 DO
        BEGIN
          FETCH my_cursor INTO Table_name;
          SET str = CONCAT(str,Table_name,',');  
        END;
    END WHILE;
    SELECT LEFT(str, LENGTH(str) - 1);
    CLOSE my_cursor;
    SELECT str;
END

不幸的是，我收到了许多错误消息：

ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '' at line 3
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'DECLARE done INT DEFAULT 0' at line 1
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'DECLARE str  LONGTEXT' at line 1
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'DECLARE my_cursor CURSOR FOR
    SELECT DISTINCT TABLE_NAME
    From INFORMATION' at line 1
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = 1' at line 1
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'OPEN my_cursor' at line 1
ERROR 1193 (HY000): Unknown system variable 'str'
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'WHILE done = 0 DO
        BEGIN
          FETCH my_cursor INTO Table_name' at line 1
ERROR 1193 (HY000): Unknown system variable 'str'
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'END' at line 1
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'END WHILE' at line 1
ERROR 1054 (42S22): Unknown column 'str' in 'field list'
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'CLOSE my_cursor' at line 1
ERROR 1054 (42S22): Unknown column 'str' in 'field list'
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'END' at line 1

我的mysql版本是5.7.12。有什么建议吗？

Answer 1

存储过程必须看起来像这样。

table_name将被放置在一个文本变量中，并且您看到的结果是逗号分隔的文本。

如果您需要一个包含行的表，则必须添加一个临时表并在末尾选择该表。

DELIMITER //
CREATE DEFINER=`root`@`localhost` PROCEDURE `MISS_CASE_CHECK`()
BEGIN
    DECLARE Tablename TEXT;
    DECLARE done INT DEFAULT 0;
    DECLARE str  LONGTEXT;
    DECLARE my_cursor CURSOR FOR
    SELECT DISTINCT TABLE_NAME
    From INFORMATION_SCHEMA.COLUMNS
    WHERE COLUMN_NAME ='Id' and TABLE_SCHEMA='testdb';

    DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = 1;
    SET @tablen = '';
    OPEN my_cursor;
   SET str = '';      
    WHILE done = 0 DO
        BEGIN
          FETCH my_cursor INTO Tablename;
          SET str = CONCAT(str,Tablename,',');  
        END;
    END WHILE;
    SELECT LEFT(str, LENGTH(str) - 1);
    CLOSE my_cursor;
END//
DELIMITER ;

Answer 2

您将无法一步一步完成此操作（除非有一些超级向后的创造方式）。取而代之的是，您将执行现有查询以获取作为第二个条件候选者的表的列表。然后，您将对该列表中的每个表发出一条SQL语句，以测试该表是否具有您的值。

您可以通过将第一个SQL语句作为一个大的UNION QUERY编写其他SQL语句来加快此速度，然后执行第二步。

类似的东西：

select DISTINCT 
    CONCAT('SELECT DISTINCT ', TABLE_NAME, ' AS table_name FROM ', TABLE_NAME, ' WHERE NOT EXISTS (SELECT 1 FROM ', TABLE_NAME, ' WHERE case_id=123) UNION ALL ') as sqlstatement 
from INFORMATION_SCHEMA.COLUMNS 
where COLUMN_NAME IN ("case_id") and TABLE_SCHEMA="test_db";

只需获取该输出，修剪最后的UNION ALL并提交（我尚未测试过，但从理论上讲，这应该可以完成工作）

如果您经常这样做，则应将其移至存储过程或其他脚本语言中，在其中循环搜索候选对象（来自原始SQL），然后发出sql查询该表以查看是否拥有case_id，并将其添加到新表/列表/数组/内容中以进行输出。

如何打印不包含ID或不包含ID列的表的名称？

2 个答案: