Question

我有一个表，其主键在其他几个表中作为外键引用。例如：

  CREATE TABLE `X` (
    `X_id` int NOT NULL auto_increment,
    `name` varchar(255) NOT NULL,
    PRIMARY KEY  (`X_id`)
  )
  CREATE TABLE `Y` (
    `Y_id` int(11) NOT NULL auto_increment,
    `name` varchar(255) NOT NULL,
    `X_id` int DEFAULT NULL,
    PRIMARY KEY  (`Y_id`),
    CONSTRAINT `Y_X` FOREIGN KEY (`X_id`) REFERENCES `X` (`X_id`)
  )
  CREATE TABLE `Z` (
    `Z_id` int(11) NOT NULL auto_increment,
    `name` varchar(255) NOT NULL,
    `X_id` int DEFAULT NULL,
    PRIMARY KEY  (`Z_id`),
    CONSTRAINT `Z_X` FOREIGN KEY (`X_id`) REFERENCES `X` (`X_id`)
  )

现在，我不知道数据库中有多少表包含X中的外键，如表Y和Z.是否有可用于返回的SQL查询：

具有外键到X
这些表中的哪些实际上在外键中有值

Answer 1

你走了：

USE information_schema;
SELECT *
FROM
  KEY_COLUMN_USAGE
WHERE
  REFERENCED_TABLE_NAME = 'X'
  AND REFERENCED_COLUMN_NAME = 'X_id';

如果您有多个具有相似表/列名称的数据库，您可能还希望将查询限制为特定数据库：

SELECT *
FROM
  KEY_COLUMN_USAGE
WHERE
  REFERENCED_TABLE_NAME = 'X'
  AND REFERENCED_COLUMN_NAME = 'X_id'
  AND TABLE_SCHEMA = 'your_database_name';

Answer 2

MySQL 5.5参考手册："InnoDB and FOREIGN KEY Constraints"

SELECT
  ke.REFERENCED_TABLE_SCHEMA parentSchema,
  ke.referenced_table_name parentTable,
  ke.REFERENCED_COLUMN_NAME parentColumnName,
  ke.TABLE_SCHEMA ChildSchema,
  ke.table_name childTable,
  ke.COLUMN_NAME ChildColumnName
FROM
  information_schema.KEY_COLUMN_USAGE ke
WHERE
  ke.referenced_table_name IS NOT NULL
  AND ke.REFERENCED_COLUMN_NAME = 'ci_id' ## Find Foreign Keys linked to this Primary Key
ORDER BY
  ke.referenced_table_name;

Answer 3

此解决方案不仅会显示所有关系，还会显示约束名称，这在某些情况下是必需的（例如，丢弃约束）：

SELECT
    CONCAT(table_name, '.', column_name) AS 'foreign key',
    CONCAT(referenced_table_name, '.', referenced_column_name) AS 'references',
    constraint_name AS 'constraint name'
FROM
    information_schema.key_column_usage
WHERE
    referenced_table_name IS NOT NULL;

如果要检查特定数据库中的表，请添加以下内容：

AND table_schema = 'database_name';

Answer 4

您可以在明智的information_schema表中找到所有与架构相关的信息。

您可能需要查看表格REFERENTIAL_CONSTRAINTS和KEY_COLUMN_USAGE。前者告诉你哪些表被其他人引用;后者会告诉你他们的领域是如何相关的。

Answer 5

我写了一些 bash onliner ，你可以写一个脚本来获得友好的输出：

mysql_references_to：

mysql -uUSER -pPASS -A DB_NAME -se "USE information_schema; SELECT * FROM KEY_COLUMN_USAGE WHERE REFERENCED_TABLE_NAME = '$1' AND REFERENCED_COLUMN_NAME = 'id'\G" | sed 's/^[ \t]*//;s/[ \t]*$//' |egrep "\<TABLE_NAME|\<COLUMN_NAME" |sed 's/TABLE_NAME: /./g' |sed 's/COLUMN_NAME: //g' | paste -sd "," -| tr '.' '\n' |sed 's/,$//' |sed 's/,/./'

执行：mysql_references_to transaccion（其中 transaccion 是一个随机表名）给出如下输出：

carrito_transaccion.transaccion_id
comanda_detalle.transaccion_id
comanda_detalle_devolucion.transaccion_positiva_id
comanda_detalle_devolucion.transaccion_negativa_id
comanda_transaccion.transaccion_id
cuenta_operacion.transaccion_id
...

Answer 6

列出数据库中的所有外键，包括说明

    SELECT  
    i1.CONSTRAINT_NAME, i1.TABLE_NAME,i1.COLUMN_NAME,
    i1.REFERENCED_TABLE_SCHEMA,i1.REFERENCED_TABLE_NAME, i1.REFERENCED_COLUMN_NAME,
    i2.UPDATE_RULE, i2.DELETE_RULE 
    FROM   
    information_schema.KEY_COLUMN_USAGE AS i1  
    INNER JOIN 
    information_schema.REFERENTIAL_CONSTRAINTS AS i2 
    ON i1.CONSTRAINT_NAME = i2.CONSTRAINT_NAME 
    WHERE i1.REFERENCED_TABLE_NAME IS NOT NULL  
    AND  i1.TABLE_SCHEMA  ='db_name';

限制到表格中的特定列

AND i1.table_name = 'target_tb_name' AND i1.column_name = 'target_col_name'

Answer 7

选择 TABLE_NAME，COLUMN_NAME FROM information_schema.KEY_COLUMN_USAGE WHERE CONSTRAINT_SCHEMA LIKE 'your_database' AND TABLE_SCHEMA LIKE 'your_database' AND REFERENCED_TABLE_SCHEMA LIKE 'your_database' AND REFERENCED_TABLE_NAME LIKE 'your_table' AND REFERENCED_COLUMN_NAME LIKE 'your_column';

Answer 8

最简单的：
1.打开phpMyAdmin
2.在左键单击数据库名称
3.在右上角找到“Designer”选项卡

所有约束都将在那里显示。

如何查找具有引用特定table.column的外键并具有这些外键值的所有表？

8 个答案: