键"PRIMARY"的条目重复.忽略字符串的空格 [英] Duplicate entry for key 'PRIMARY' .Ignoring the spaces for strings

问题描述

mysql> CREATE TABLE primary2(boom text,id int,PRIMARY KEY(boom(5)) );
Query OK, 0 rows affected (0.04 sec)

mysql> INSERT INTO primary2 VALUES('viok',1);
Query OK, 1 row affected (0.00 sec)

mysql> INSERT INTO primary2 VALUES('viok',1);
ERROR 1062 (23000): Duplicate entry 'viok' for key 'PRIMARY'
mysql> INSERT INTO primary2 VALUES('viok ',1);
ERROR 1062 (23000): Duplicate entry 'viok ' for key 'PRIMARY'

STRING的"viok"和"viok"不同.如何添加带空格的字符串?

STRINGs 'viok' and 'viok ' are different .How to add a string with spaces?

推荐答案

问:如何添加带空格的字符串?

Q: How to add a string with spaces?

A:这是不可能的.

就MySQL如何将它们存储为索引条目而言，TEXT值'viok'和'viok'不是唯一的.这是已记录的行为:

The TEXT values 'viok' and 'viok ' are not unique, in terms of how MySQL stores those as index entries. This is documented behavior:

如果为TEXT列建立索引，则索引条目比较将在末尾加空格.这意味着，如果索引要求唯一值，则仅尾随空格数量不同的值将发生重复键错误.例如，如果表包含"a"，则尝试存储"a"会导致重复键错误.对于BLOB列，情况并非如此.

If a TEXT column is indexed, index entry comparisons are space-padded at the end. This means that, if the index requires unique values, duplicate-key errors will occur for values that differ only in the number of trailing spaces. For example, if a table contains 'a', an attempt to store 'a ' causes a duplicate-key error. This is not true for BLOB columns.

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