SQL for commonly used database queries to determine whether tables and fields exist

SQL for commonly used database queries to determine whether tables and fields exist (if the result is 1, it means it exists, and 0 means it does not exist)

1. MSSQL Server
Table:

SELECT COUNT(*) FROM dbo.sysobjects 
WHERE name= 'table_name';

Field:

SELECT COUNT(*) FROM syscolumns 
WHERE id=object_id(‘table_name’) AND name= 'column_name';

2. My SQL
Table:

SELECT COUNT(*) FROM information_schema.tables 
WHERE table_name ='table_name';

Field:

SELECT COUNT(*) FROM information_schema.columns 
WHERE table_name ='table_name' AND column_name ='column_name';

3. Oracle
Table:

SELECT count(*) FROM USER_OBJECTS 
WHERE OBJECT_NAME = 'table_name';

Field:

SELECT COUNT(*) FROM USER_TAB_COLUMNS 
WHERE TABLE_NAME ='table_name' AND column_name ='column_name';

4. PostgreSql
Table:

SELECT count(*) FROM information_schema.tables 
WHERE table_schema='table_schema' AND table_name ='table_name';

Field:

SELECT count(*) FROM information_schema.columns 
WHERE table_schema='table_schema' AND table_name ='table_name' AND column_name='column_name';