CREATE TABLE t3 ( s1 INT, s2 INT, s3 INT, KEY(s1), CONSTRAINT CO FOREIGN KEY (s2) REFERENCES t1(s3) ) ENGINE=InnoDB; 

For those two tables, the KEY_COLUMN_USAGE  table has two rows: 

•One row with CONSTRAINT_NAME  = ’PRIMARY’ , TABLE_NAME  = ’t1’ , COLUMN_NAME  = ’s3’ , ORDINAL_POSITION  = 1 , POSITION_IN_UNIQUE_CONSTRAINT  = NULL . 

For NDB : This value is always NULL . 

•One row with CONSTRAINT_NAME  = ’CO’ , TABLE_NAME  = ’t3’ , COLUMN_NAME  = ’s2’ , ORDINAL_POSITION  = 1 , POSITION_IN_UNIQUE_CONSTRAINT  = 1 . 

## 26.3.17 The INFORMATION_SCHEMA KEYWORDS Table 

The KEYWORDS  table lists the words considered keywords by MySQL and, for each one, indicates whether it is reserved. Reserved keywords may require special treatment in some contexts, such as special quoting when used as identifiers (see Section 9.3, “Keywords and Reserved Words” ). This table provides applications a runtime source of MySQL keyword information. 

Prior to MySQL 8.0.13, selecting from the KEYWORDS  table with no default database selected produced an error. (Bug #90160, Bug #27729859) 

The KEYWORDS  table has these columns: 

• WORD 

The keyword. 

• RESERVED 

An integer indicating whether the keyword is reserved (1) or nonreserved (0). 

These queries lists all keywords, all reserved keywords, and all nonreserved keywords, respectively: 

SELECT * FROM INFORMATION_SCHEMA.KEYWORDS; SELECT WORD FROM INFORMATION_SCHEMA.KEYWORDS WHERE RESERVED = 1; SELECT WORD FROM INFORMATION_SCHEMA.KEYWORDS WHERE RESERVED = 0; 

The latter two queries are equivalent to: 

SELECT WORD FROM INFORMATION_SCHEMA.KEYWORDS WHERE RESERVED; SELECT WORD FROM INFORMATION_SCHEMA.KEYWORDS WHERE NOT RESERVED; 

If you build MySQL from source, the build process generates a keyword_list.h  header file containing an array of keywords and their reserved status. This file can be found in the sql  directory under the build directory. This file may be useful for applications that require a static source for the keyword list. 

## 26.3.18 The INFORMATION_SCHEMA ndb_transid_mysql_connection_map Table 

The ndb_transid_mysql_connection_map  table provides a mapping between NDB  transactions, NDB transaction coordinators, and MySQL Servers attached to an NDB Cluster as API nodes. This information 

