如何获取 MySQL 中表的当前 AUTO_INCREMENT 值?
9 回答
您可以使用以下查询获取所有表数据:
SHOW TABLE STATUS FROM `DatabaseName` WHERE `name` LIKE 'TableName' ;
您可以使用以下查询准确获取此信息:
SELECT `AUTO_INCREMENT`
FROM INFORMATION_SCHEMA.TABLES
WHERE TABLE_SCHEMA = 'DatabaseName'
AND TABLE_NAME = 'TableName';
如果您只想知道数字,而不是在查询中获取它,那么您可以使用:
SHOW CREATE TABLE tablename;
您应该在底部看到 auto_increment
我相信您正在寻找 MySQL 的LAST_INSERT_ID()函数。如果在命令行中,只需运行以下命令:
LAST_INSERT_ID();
您还可以通过 SELECT 查询获取此值:
SELECT LAST_INSERT_ID();
即使如果您手动运行查询, methai的答案是正确的,但当 2 个并发事务/连接在生产运行时实际执行此查询时(例如),就会出现问题。
刚刚在 MySQL 工作台中手动尝试,同时打开了 2 个连接:
CREATE TABLE translation (
id BIGINT PRIMARY KEY AUTO_INCREMENT
);
# Suppose we have already 20 entries, we execute 2 new inserts:
交易一:
21 = SELECT `AUTO_INCREMENT` FROM INFORMATION_SCHEMA.TABLES
WHERE TABLE_SCHEMA = 'DatabaseName' AND TABLE_NAME = 'translation';
insert into translation (id) values (21);
交易2:
21 = SELECT `AUTO_INCREMENT` FROM INFORMATION_SCHEMA.TABLES
WHERE TABLE_SCHEMA = 'DatabaseName' AND TABLE_NAME = 'translation';
insert into translation (id) values (21);
# commit transaction 1;
# commit transaction 2;
- 插入事务 1 正常
- 插入事务 2 出错:错误代码:1062。密钥“PRIMARY”的重复条目“21”。
一个好的解决方案是jvdub的答案,因为每个事务/连接的 2 个插入将是:
交易一:
insert into translation (id) values (null);
21 = SELECT LAST_INSERT_ID();
交易2:
insert into translation (id) values (null);
22 = SELECT LAST_INSERT_ID();
# commit transaction 1;
# commit transaction 2;
但是我们必须在插入之后执行last_insert_id()!我们可以重用该 id 以插入到其他需要外键的表中!
此外,我们无法执行以下 2 个查询:
insert into translation (id) values ((SELECT AUTO_INCREMENT FROM
information_schema.TABLES WHERE TABLE_SCHEMA=DATABASE()
AND TABLE_NAME='translation'));
因为我们实际上有兴趣在其他表中获取/重用该 ID 或返回!
编辑:2021 年 2 月 8 日,检索值
要实际检索应用程序中的值(在 Java 中使用 MyBatis 完成的示例):
@Mapper
public interface ClientMapper {
@Select("select last_insert_id()")
Long getLastInsertedId();
@Insert({...})
void insertClientInfo(ClientInfo client);
}
然后在存储库中
public void insertClientInfo(ClientInfo clientInfo) {
mapper.insertClientInfo(clientInfo);
Long pk = mapper.getLastInsertedId();
clientInfo.setId(pk);
}
mysqli 可执行示例代码:
<?php
$db = new mysqli("localhost", "user", "password", "YourDatabaseName");
if ($db->connect_errno) die ($db->connect_error);
$table=$db->prepare("SHOW TABLE STATUS FROM YourDatabaseName");
$table->execute();
$sonuc = $table->get_result();
while ($satir=$sonuc->fetch_assoc()){
if ($satir["Name"]== "YourTableName"){
$ai[$satir["Name"]]=$satir["Auto_increment"];
}
}
$LastAutoIncrement=$ai["YourTableName"];
echo $LastAutoIncrement;
?>
查询以检查一个给定模式的所有表的 AUTO_INCREMENT 百分比“使用”(除了类型为bigint unsigned的列):
SELECT
c.TABLE_NAME,
c.COLUMN_TYPE,
c.MAX_VALUE,
t.AUTO_INCREMENT,
IF (c.MAX_VALUE > 0, ROUND(100 * t.AUTO_INCREMENT / c.MAX_VALUE, 2), -1) AS "Usage (%)"
FROM
(SELECT
TABLE_SCHEMA,
TABLE_NAME,
COLUMN_TYPE,
CASE
WHEN COLUMN_TYPE LIKE 'tinyint(1)' THEN 127
WHEN COLUMN_TYPE LIKE 'tinyint(1) unsigned' THEN 255
WHEN COLUMN_TYPE LIKE 'smallint(%)' THEN 32767
WHEN COLUMN_TYPE LIKE 'smallint(%) unsigned' THEN 65535
WHEN COLUMN_TYPE LIKE 'mediumint(%)' THEN 8388607
WHEN COLUMN_TYPE LIKE 'mediumint(%) unsigned' THEN 16777215
WHEN COLUMN_TYPE LIKE 'int(%)' THEN 2147483647
WHEN COLUMN_TYPE LIKE 'int(%) unsigned' THEN 4294967295
WHEN COLUMN_TYPE LIKE 'bigint(%)' THEN 9223372036854775807
WHEN COLUMN_TYPE LIKE 'bigint(%) unsigned' THEN 0
ELSE 0
END AS "MAX_VALUE"
FROM
INFORMATION_SCHEMA.COLUMNS
WHERE EXTRA LIKE '%auto_increment%'
) c
JOIN INFORMATION_SCHEMA.TABLES t ON (t.TABLE_SCHEMA = c.TABLE_SCHEMA AND t.TABLE_NAME = c.TABLE_NAME)
WHERE
c.TABLE_SCHEMA = 'YOUR_SCHEMA'
ORDER BY
`Usage (%)` DESC;
如果列在 sql server 中自动递增,那么要查看当前的自动递增值,并且如果要编辑该列的值,请使用以下查询。
-- to get current value
select ident_current('Table_Name')
-- to update current value
dbcc checkident ('[Table_Name]',reseed,"Your Value")
我一直在寻找相同的方法,并最终在 Helper 类中创建了一个静态方法(在我的例子中,我将其命名为 App\Helpers\Database)。
方法
/**
* Method to get the autoincrement value from a database table
*
* @access public
*
* @param string $database The database name or configuration in the .env file
* @param string $table The table name
*
* @return mixed
*/
public static function getAutoIncrementValue($database, $table)
{
$database ?? env('DB_DATABASE');
return \DB::select("
SELECT AUTO_INCREMENT
FROM information_schema.TABLES
WHERE TABLE_SCHEMA = '" . env('DB_DATABASE') . "'
AND TABLE_NAME = '" . $table . "'"
)[0]->AUTO_INCREMENT;
}
要调用该方法并获取 MySql AUTO_INCREMENT,只需使用以下命令:
$auto_increment = \App\Helpers\Database::getAutoIncrementValue(env('DB_DATABASE'), 'your_table_name');
希望能帮助到你。
列出 dbname 所有 tabename 和 AUTO_INCREMENT
SELECT `AUTO_INCREMENT`,`TABLE_NAME`
FROM INFORMATION_SCHEMA.TABLES
WHERE TABLE_SCHEMA = 'dbname' ORDER BY AUTO_INCREMENT desc