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25.42 Extensions to SHOW Statements

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Some extensions to SHOW statements accompany the implementation of INFORMATION_SCHEMA:

  • SHOW can be used to get information about the structure of INFORMATION_SCHEMA itself.

  • Several SHOW statements accept a WHERE clause that provides more flexibility in specifying which rows to display.

INFORMATION_SCHEMA is an information database, so its name is included in the output from SHOW DATABASES. Similarly, SHOW TABLES can be used with INFORMATION_SCHEMA to obtain a list of its tables:

  1. mysql> SHOW TABLES FROM INFORMATION_SCHEMA;
  2. +---------------------------------------+
  3. | Tables_in_INFORMATION_SCHEMA          |
  4. +---------------------------------------+
  5. | CHARACTER_SETS                        |
  6. | COLLATIONS                            |
  7. | COLLATION_CHARACTER_SET_APPLICABILITY |
  8. | COLUMNS                               |
  9. | COLUMN_PRIVILEGES                     |
  10. | ENGINES                               |
  11. | EVENTS                                |
  12. | FILES                                 |
  13. | KEY_COLUMN_USAGE                      |
  14. | PARTITIONS                            |
  15. | PLUGINS                               |
  16. | PROCESSLIST                           |
  17. | REFERENTIAL_CONSTRAINTS               |
  18. | ROUTINES                              |
  19. | SCHEMATA                              |
  20. | SCHEMA_PRIVILEGES                     |
  21. | STATISTICS                            |
  22. | TABLES                                |
  23. | TABLE_CONSTRAINTS                     |
  24. | TABLE_PRIVILEGES                      |
  25. | TRIGGERS                              |
  26. | USER_PRIVILEGES                       |
  27. | VIEWS                                 |
  28. +---------------------------------------+

SHOW COLUMNS and DESCRIBE can display information about the columns in individual INFORMATION_SCHEMA tables.

SHOW statements that accept a LIKE clause to limit the rows displayed also permit a WHERE clause that specifies more general conditions that selected rows must satisfy:

  1. SHOW CHARACTER SET
  2. SHOW COLLATION
  3. SHOW COLUMNS
  4. SHOW DATABASES
  5. SHOW FUNCTION STATUS
  6. SHOW INDEX
  7. SHOW OPEN TABLES
  8. SHOW PROCEDURE STATUS
  9. SHOW STATUS
  10. SHOW TABLE STATUS
  11. SHOW TABLES
  12. SHOW TRIGGERS
  13. SHOW VARIABLES

The WHERE clause, if present, is evaluated against the column names displayed by the SHOW statement. For example, the SHOW CHARACTER SET statement produces these output columns:

  1. mysql> SHOW CHARACTER SET;
  2. +----------+-----------------------------+---------------------+--------+
  3. | Charset  | Description                 | Default collation   | Maxlen |
  4. +----------+-----------------------------+---------------------+--------+
  5. | big5     | Big5 Traditional Chinese    | big5_chinese_ci     |      2 |
  6. | dec8     | DEC West European           | dec8_swedish_ci     |      1 |
  7. | cp850    | DOS West European           | cp850_general_ci    |      1 |
  8. | hp8      | HP West European            | hp8_english_ci      |      1 |
  9. | koi8r    | KOI8-R Relcom Russian       | koi8r_general_ci    |      1 |
  10. | latin1   | cp1252 West European        | latin1_swedish_ci   |      1 |
  11. | latin2   | ISO 8859-2 Central European | latin2_general_ci   |      1 |
  12. ...

To use a WHERE clause with SHOW CHARACTER SET, you would refer to those column names. As an example, the following statement displays information about character sets for which the default collation contains the string 'japanese':

  1. mysql> SHOW CHARACTER SET WHERE `Default collation` LIKE '%japanese%';
  2. +---------+---------------------------+---------------------+--------+
  3. | Charset | Description               | Default collation   | Maxlen |
  4. +---------+---------------------------+---------------------+--------+
  5. | ujis    | EUC-JP Japanese           | ujis_japanese_ci    |      3 |
  6. | sjis    | Shift-JIS Japanese        | sjis_japanese_ci    |      2 |
  7. | cp932   | SJIS for Windows Japanese | cp932_japanese_ci   |      2 |
  8. | eucjpms | UJIS for Windows Japanese | eucjpms_japanese_ci |      3 |
  9. +---------+---------------------------+---------------------+--------+

This statement displays the multibyte character sets:

  1. mysql> SHOW CHARACTER SET WHERE Maxlen > 1;
  2. +---------+---------------------------+---------------------+--------+
  3. | Charset | Description               | Default collation   | Maxlen |
  4. +---------+---------------------------+---------------------+--------+
  5. | big5    | Big5 Traditional Chinese  | big5_chinese_ci     |      2 |
  6. | ujis    | EUC-JP Japanese           | ujis_japanese_ci    |      3 |
  7. | sjis    | Shift-JIS Japanese        | sjis_japanese_ci    |      2 |
  8. | euckr   | EUC-KR Korean             | euckr_korean_ci     |      2 |
  9. | gb2312  | GB2312 Simplified Chinese | gb2312_chinese_ci   |      2 |
  10. | gbk     | GBK Simplified Chinese    | gbk_chinese_ci      |      2 |
  11. | utf8    | UTF-8 Unicode             | utf8_general_ci     |      3 |
  12. | ucs2    | UCS-2 Unicode             | ucs2_general_ci     |      2 |
  13. | cp932   | SJIS for Windows Japanese | cp932_japanese_ci   |      2 |
  14. | eucjpms | UJIS for Windows Japanese | eucjpms_japanese_ci |      3 |
  15. +---------+---------------------------+---------------------+--------+

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Document created the 26/06/2006, last modified the 26/10/2018
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