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

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Release: 2016-11-12 09:34:16
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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';
Copy after login

Field:

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


2. My SQL
Table:

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

Field:

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


3. Oracle
Table:

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

Field:

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


4. PostgreSql
Table:

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

Field:

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