小编OMG*_*ies的帖子

我正在运行的查询如下,但是我收到此错误:

#1054 - 'IN/ALL/ANY子查询'中的未知列'guaranteed_postcode'

SELECT `users`.`first_name`, `users`.`last_name`, `users`.`email`,
SUBSTRING(`locations`.`raw`,-6,4) AS `guaranteed_postcode`
FROM `users` LEFT OUTER JOIN `locations`
ON `users`.`id` = `locations`.`user_id`
WHERE `guaranteed_postcode` NOT IN #this is where the fake col is being used
(
 SELECT `postcode` FROM `postcodes` WHERE `region` IN
 (
  'australia'
 )
)

我的问题是:为什么我无法在同一个数据库查询的where子句中使用假列？

为什么在DEFAULT或ON UPDATE子句中只能有一个TIMESTAMP列和CURRENT_TIMESTAMP？

CREATE TABLE `foo` (
  `ProductID` INT(10) UNSIGNED NOT NULL,
  `AddedDate` TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
  `UpdatedDate` TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP
) ENGINE=INNODB;

导致的错误:

错误代码:1293

表定义不正确; 在DEFAULT或ON UPDATE子句中只能有一个TIMESTAMP列和CURRENT_TIMESTAMP

我有以下表架构,它将user_customers映射到实时MySQL数据库的权限:

mysql> describe user_customer_permission;
+------------------+---------+------+-----+---------+----------------+
| Field            | Type    | Null | Key | Default | Extra          |
+------------------+---------+------+-----+---------+----------------+
| id               | int(11) | NO   | PRI | NULL    | auto_increment |
| user_customer_id | int(11) | NO   | PRI | NULL    |                |
| permission_id    | int(11) | NO   | PRI | NULL    |                |
+------------------+---------+------+-----+---------+----------------+
3 rows in set (0.00 sec)

我想删除user_customer_id和permission_id的主键,并保留id的主键.

当我运行命令时:

alter table user_customer_permission drop primary key;

我收到以下错误:

ERROR 1075 (42000): Incorrect table definition; there can …

如何使用SQL Server Management Studio创建复合键？

我想要两个INT列来形成表的标识(唯一)

我在mysql中试过这个:

mysql> alter table region drop column country_id;

得到了这个:

ERROR 1025 (HY000): Error on rename of './product/#sql-14ae_81' to
'./product/region' (errno: 150)

有任何想法吗？外键的东西？

在处理性能更好的大型数据库时,IN还是OR在SQL Where-clause中？

他们的执行方式有什么不同吗？

我在linux机箱上安装了mysql服务器IP = 192.168.1.100但是当我尝试连接到这个IP时它总是错误(111).但是使用localhost和127.0.0.1就可以了.

beer@beer-laptop# ifconfig | grep "inet addr"
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet addr:192.168.1.100  Bcast:192.168.1.255  Mask:255.255.255.0

beer@beer-laptop# mysql -ubeer -pbeer -h192.168.1.100
ERROR 2003 (HY000): Can't connect to MySQL server on '192.168.1.100' (111)

beer@beer-laptop# mysql -ubeer -pbeer -hlocalhost
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 160
Server version: 5.1.31-1ubuntu2 (Ubuntu)

Type 'help;' or '\h' for help. Type '\c' to clear the buffer.

mysql> 

beer@beer-laptop# mysql -ubeer -pbeer -h127.0.0.1
Welcome to the MySQL …

假设我有两张桌子:

Table: Color
Columns: Id, ColorName, ColorCode

Table: Shape
Columns: Id, ShapeName, VertexList

我该怎么称呼将颜色映射到形状的表格？

Table: ???
Columns: ColorId, ShapeId

我有以下表模式;

CREATE TABLE `db1`.`sms_queue` (
  `Id` INTEGER UNSIGNED NOT NULL AUTO_INCREMENT,
  `Message` VARCHAR(160) NOT NULL DEFAULT 'Unknown Message Error',
  `CurrentState` VARCHAR(10) NOT NULL DEFAULT 'None',
  `Phone` VARCHAR(14) DEFAULT NULL,
  `Created` TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
  `LastUpdated` TIMESTAMP NOT NULL ON UPDATE CURRENT_TIMESTAMP,
  `TriesLeft` tinyint NOT NULL DEFAULT 3,
  PRIMARY KEY (`Id`)
)
ENGINE = InnoDB;

它失败并出现以下错误:

ERROR 1293 (HY000): Incorrect table definition; there can be only one TIMESTAMP column with CURRENT_TIMESTAMP in DEFAULT or ON UPDATE clause.

我的问题是,我可以同时拥有这两个领域吗？或者我必须在每次交易期间手动设置LastUpdated字段？

有没有"简单"的方法来做到这一点,或者我需要传递一个带有"OUTPUT ... INTO"语法的表变量？

DECLARE @someInt int

INSERT INTO MyTable2(AIntColumn)
OUTPUT @SomeInt = Inserted.AIntColumn
VALUES(12)