Edit File: is_cml_memory.result
SET @@session.sql_mode = 'NO_ENGINE_SUBSTITUTION'; USE test; DROP TABLE IF EXISTS t1; CREATE TABLE t1 ( f1 CHAR UNICODE, f2 CHAR(0) UNICODE, f3 CHAR(10) UNICODE, f5 VARCHAR(0) UNICODE, f6 VARCHAR(255) UNICODE, f7 VARCHAR(260) UNICODE ) ENGINE = MEMORY; SELECT * FROM information_schema.columns WHERE table_schema LIKE 'test%' ORDER BY table_schema, table_name, column_name; TABLE_CATALOG TABLE_SCHEMA TABLE_NAME COLUMN_NAME ORDINAL_POSITION COLUMN_DEFAULT IS_NULLABLE DATA_TYPE CHARACTER_MAXIMUM_LENGTH CHARACTER_OCTET_LENGTH NUMERIC_PRECISION NUMERIC_SCALE CHARACTER_SET_NAME COLLATION_NAME COLUMN_TYPE COLUMN_KEY EXTRA PRIVILEGES COLUMN_COMMENT def test t1 f1 1 NULL YES char 1 2 NULL NULL ucs2 ucs2_general_ci char(1) select,insert,update,references def test t1 f2 2 NULL YES char 0 0 NULL NULL ucs2 ucs2_general_ci char(0) select,insert,update,references def test t1 f3 3 NULL YES char 10 20 NULL NULL ucs2 ucs2_general_ci char(10) select,insert,update,references def test t1 f5 4 NULL YES varchar 0 0 NULL NULL ucs2 ucs2_general_ci varchar(0) select,insert,update,references def test t1 f6 5 NULL YES varchar 255 510 NULL NULL ucs2 ucs2_general_ci varchar(255) select,insert,update,references def test t1 f7 6 NULL YES varchar 260 520 NULL NULL ucs2 ucs2_general_ci varchar(260) select,insert,update,references ########################################################################## # Show the quotient of CHARACTER_OCTET_LENGTH and CHARACTER_MAXIMUM_LENGTH ########################################################################## SELECT DISTINCT CHARACTER_OCTET_LENGTH / CHARACTER_MAXIMUM_LENGTH AS COL_CML, DATA_TYPE, CHARACTER_SET_NAME, COLLATION_NAME FROM information_schema.columns WHERE table_schema LIKE 'test%' AND CHARACTER_OCTET_LENGTH / CHARACTER_MAXIMUM_LENGTH = 1 ORDER BY CHARACTER_SET_NAME, COLLATION_NAME, COL_CML; COL_CML DATA_TYPE CHARACTER_SET_NAME COLLATION_NAME SELECT DISTINCT CHARACTER_OCTET_LENGTH / CHARACTER_MAXIMUM_LENGTH AS COL_CML, DATA_TYPE, CHARACTER_SET_NAME, COLLATION_NAME FROM information_schema.columns WHERE table_schema LIKE 'test%' AND CHARACTER_OCTET_LENGTH / CHARACTER_MAXIMUM_LENGTH <> 1 ORDER BY CHARACTER_SET_NAME, COLLATION_NAME, COL_CML; COL_CML DATA_TYPE CHARACTER_SET_NAME COLLATION_NAME 2.0000 char ucs2 ucs2_general_ci 2.0000 varchar ucs2 ucs2_general_ci SELECT DISTINCT CHARACTER_OCTET_LENGTH / CHARACTER_MAXIMUM_LENGTH AS COL_CML, DATA_TYPE, CHARACTER_SET_NAME, COLLATION_NAME FROM information_schema.columns WHERE table_schema LIKE 'test%' AND CHARACTER_OCTET_LENGTH / CHARACTER_MAXIMUM_LENGTH IS NULL ORDER BY CHARACTER_SET_NAME, COLLATION_NAME, COL_CML; COL_CML DATA_TYPE CHARACTER_SET_NAME COLLATION_NAME NULL char ucs2 ucs2_general_ci NULL varchar ucs2 ucs2_general_ci --> CHAR(0) is allowed (see manual), and here both CHARACHTER_* values --> are 0, which is intended behavior, and the result of 0 / 0 IS NULL SELECT CHARACTER_OCTET_LENGTH / CHARACTER_MAXIMUM_LENGTH AS COL_CML, TABLE_SCHEMA, TABLE_NAME, COLUMN_NAME, DATA_TYPE, CHARACTER_MAXIMUM_LENGTH, CHARACTER_OCTET_LENGTH, CHARACTER_SET_NAME, COLLATION_NAME, COLUMN_TYPE FROM information_schema.columns WHERE table_schema LIKE 'test%' ORDER BY TABLE_SCHEMA, TABLE_NAME, ORDINAL_POSITION; COL_CML TABLE_SCHEMA TABLE_NAME COLUMN_NAME DATA_TYPE CHARACTER_MAXIMUM_LENGTH CHARACTER_OCTET_LENGTH CHARACTER_SET_NAME COLLATION_NAME COLUMN_TYPE 2.0000 test t1 f1 char 1 2 ucs2 ucs2_general_ci char(1) NULL test t1 f2 char 0 0 ucs2 ucs2_general_ci char(0) 2.0000 test t1 f3 char 10 20 ucs2 ucs2_general_ci char(10) NULL test t1 f5 varchar 0 0 ucs2 ucs2_general_ci varchar(0) 2.0000 test t1 f6 varchar 255 510 ucs2 ucs2_general_ci varchar(255) 2.0000 test t1 f7 varchar 260 520 ucs2 ucs2_general_ci varchar(260) DROP TABLE t1;
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