CREATE TABLE t (
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s1 VARCHAR(20) DEFAULT 'ABC',
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s2 VARCHAR(20) DEFAULT (concat('A','B')),
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s3 VARCHAR(20) DEFAULT ("concat('A','B')"),
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s4 VARCHAR(20),
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s5 VARCHAR(20) DEFAULT NULL,
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s6 VARCHAR(20) NOT NULL,
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s7 VARCHAR(20) DEFAULT 'NULL' NULL,
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s8 VARCHAR(20) DEFAULT 'NULL' NOT NULL
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);
|
|
SELECT
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table_name,
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column_name,
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ordinal_position,
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column_default,
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column_default IS NULL
|
FROM information_schema.COLUMNS
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WHERE table_schema=DATABASE()
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AND TABLE_NAME='t';
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+------------+-------------+------------------+-----------------------+------------------------+
|
| table_name | column_name | ordinal_position | column_default | column_default IS NULL |
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+------------+-------------+------------------+-----------------------+------------------------+
|
| t | s1 | 1 | 'ABC' | 0 |
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| t | s2 | 2 | concat('A','B') | 0 |
|
| t | s3 | 3 | 'concat(''A'',''B'')' | 0 |
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| t | s4 | 4 | NULL | 0 |
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| t | s5 | 5 | NULL | 0 |
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| t | s6 | 6 | NULL | 1 |
|
| t | s7 | 7 | 'NULL' | 0 |
|
| t | s8 | 8 | 'NULL' | 0 |
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+------------+-------------+------------------+-----------------------+------------------------+
|
8 rows in set (0.001 sec)
|
|
DESC t;
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+-------+-------------+------+-----+-----------------+-------+
|
| Field | Type | Null | Key | Default | Extra |
|
+-------+-------------+------+-----+-----------------+-------+
|
| s1 | varchar(20) | YES | | ABC | |
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| s2 | varchar(20) | YES | | concat('A','B') | |
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| s3 | varchar(20) | YES | | concat('A','B') | |
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| s4 | varchar(20) | YES | | NULL | |
|
| s5 | varchar(20) | YES | | NULL | |
|
| s6 | varchar(20) | NO | | NULL | |
|
| s7 | varchar(20) | YES | | NULL | |
|
| s8 | varchar(20) | NO | | NULL | |
|
+-------+-------------+------+-----+-----------------+-------+
|