Question

预准备语句是否忽略字符串引入器？

我做了以下测试，似乎就是这种情况。我错过了什么吗？

/*Setting the variables*/
SET @str1 = _utf8mb4'some text' COLLATE utf8mb4_bin;
SET @str2 = _utf16'some text' COLLATE utf16_unicode_ci;
SET @@CHARACTER_SET_CLIENT = 'cp1250';
SET @@CHARACTER_SET_CONNECTION = 'ucs2';
SET @@COLLATION_CONNECTION = 'ucs2_unicode_ci';
SET @@CHARACTER_SET_RESULTS = 'ascii';

/*Preparing the prepared statement*/
PREPARE showStringInfo FROM 'SELECT
                               ?            `Input`,
                               CHARSET(?)   `Input Character Set`,
                               COLLATION(?) `Input Collation`,
                               @@CHARACTER_SET_CLIENT,
                               @@CHARACTER_SET_CONNECTION,
                               @@COLLATION_CONNECTION,
                               @@CHARACTER_SET_RESULTS;';

执行

EXECUTE showStringInfo
USING @str1, @str1, @str1;

结果

| some text | ucs2 | ucs2_unicode_ci | cp1250 | ucs2 | ucs2_unicode_ci | ascii

执行

EXECUTE showStringInfo
USING @str2, @str2, @str2;

结果

 s???? | ucs2 | ucs2_unicode_ci | cp1250 | ucs2 | ucs2_unicode_ci | ascii

查询时

SELECT
  @str1            `Input`,
  CHARSET(@str1)   `Input Character Set`,
  COLLATION(@str1) `Input Collation`,
  @@CHARACTER_SET_CLIENT,
  @@CHARACTER_SET_CONNECTION,
  @@COLLATION_CONNECTION,
  @@CHARACTER_SET_RESULTS;

结果

some text | utf8mb4 | utf8mb4_bin | cp1250 | ucs2 | ucs2_unicode_ci | ascii

查询

SELECT
  @str2            `Input`,
  CHARSET(@str2)   `Input Character Set`,
  COLLATION(@str2) `Input Collation`,
  @@CHARACTER_SET_CLIENT,
  @@CHARACTER_SET_CONNECTION,
  @@COLLATION_CONNECTION,
  @@CHARACTER_SET_RESULTS;

结果

s???? | utf16 | utf16_unicode_ci | cp1250 | ucs2 | ucs2_unicode_ci | ascii

测试似乎表明存储过程假定字符串为@@ CHARACTER_SET_CONNECTION和@@ COLLATION_CONNECTION，无论介绍人如何

（使用DataGrip的JDBC和mysql.exe测试）

MySQL - 准备好的语句和字符串介绍人

0 个答案: