MySQL 中 auto_increment(整数)的限制是多少?
mysqlmysqli database
auto_increment 整数的限制取决于列数据类型。显示如下:
The data type TINYINT range is 127 The data type UNSIGNED TINYINT range is 255 The data type SMALLINT range is 32767 The data type UNSIGNED SMALLINT range is 65535 The data type MEDIUMINT range is 8388607 The data type UNSIGNED MEDIUMINT range is 16777215 The data type INT range is 2147483647 The data type UNSIGNED INT range is 4294967295 The data type BIGINT range is 9223372036854775807 The data type UNSIGNED BIGINT range is 18446744073709551615
我们以 TINYINT 为例。如果你给出的值超过 127，那么 MySQL 就会出错。
我们首先创建一个表。创建表的查询如下. Here, the ID is auto_incerement:
mysql> create table LimitOfAutoIncrement -> ( -> Id TINYINT NOT NULL AUTO_INCREMENT, -> PRIMARY KEY(Id) -> ); Query OK, 0 rows affected (0.68 sec)
仅插入 127 条记录，这是 TINYINT 中 auto_increment 的限制。查询如下:
mysql> insert into LimitOfAutoIncrement values(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(); Query OK, 127 rows affected (0.20 sec) Records: 127 Duplicates: 0 Warnings: 0
使用 select 语句显示表中的所有记录。查询如下:
mysql> select *from LimitOfAutoIncrement;
输出结果如下:
+-----+ | Id | +-----+ | 1 | | 2 | | 3 | | 4 | | 5 | | 6 | | 7 | | 8 | | 9 | | 10 | | 11 | | 12 | | 13 | | 14 | | 15 | | 16 | | 17 | | 18 | | 19 | | 20 | | 21 | | 22 | | 23 | | 24 | | 25 | | 26 | | 27 | | 28 | | 29 | | 30 | | 31 | | 32 | | 33 | | 34 | | 35 | | 36 | | 37 | | 38 | | 39 | | 40 | | 41 | | 42 | | 43 | | 44 | | 45 | | 46 | | 47 | | 48 | | 49 | | 50 | | 51 | | 52 | | 53 | | 54 | | 55 | | 56 | | 57 | | 58 | | 59 | | 60 | | 61 | | 62 | | 63 | | 64 | | 65 | | 66 | | 67 | | 68 | | 69 | | 70 | | 71 | | 72 | | 73 | | 74 | | 75 | | 76 | | 77 | | 78 | | 79 | | 80 | | 81 | | 82 | | 83 | | 84 | | 85 | | 86 | | 87 | | 88 | | 89 | | 90 | | 91 | | 92 | | 93 | | 94 | | 95 | | 96 | | 97 | | 98 | | 99 | | 100 | | 101 | | 102 | | 103 | | 104 | | 105 | | 106 | | 107 | | 108 | | 109 | | 110 | | 111 | | 112 | | 113 | | 114 | | 115 | | 116 | | 117 | | 118 | | 119 | | 120 | | 121 | | 122 | | 123 | | 124 | | 125 | | 126 | | 127 | +-----+ 127 rows in set (0.00 sec)
现在您无法为 auto_increment 插入记录。如果您尝试，则会产生错误:
mysql> insert into LimitOfAutoIncrement values(); ERROR 1062 (23000): Duplicate entry '127' for key 'PRIMARY'
