：SQL查詢一張表的全部字段名稱、類型、長度

Oracle數據庫：

SELECT column_name, data_type, data_length 
FROM all_tab_columns 
WHERE table_name = 'YOUR_TABLE_NAME'
ORDER BY column_id;

MySQL/MariaDB數據庫：

SELECT COLUMN_NAME, DATA_TYPE, CHARACTER_MAXIMUM_LENGTH 
FROM INFORMATION_SCHEMA.COLUMNS 
WHERE TABLE_SCHEMA = 'YOUR_DATABASE_NAME'
AND TABLE_NAME = 'YOUR_TABLE_NAME';

SQL Server數據庫：

SELECT COLUMN_NAME, DATA_TYPE, CHARACTER_MAXIMUM_LENGTH 
FROM INFORMATION_SCHEMA.COLUMNS 
WHERE TABLE_NAME = 'YOUR_TABLE_NAME';

PostgreSQL數據庫：

SELECT column_name, data_type, character_maximum_length 
FROM information_schema.columns 
WHERE table_name = 'your_table_name';

DM(達夢)數據庫：

SELECT atc.COLUMN_NAME, atc.DATA_TYPE, atc.DATA_LENGTH 
FROM ALL_TAB_COLUMNS atc 
WHERE atc.TABLE_NAME = 'YOUR_TABLE_NAME';

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