How to check if a value exists in one of two database tables

1. How do you check if a given data exists in multiple tables?
2. How do I check if two tables have the same data in SQL?
3. How do you check if a value exists in a table SQL?
4. How do you find common data in two tables?
5. How do I check if a stored procedure exists?
6. How do you check if a column exists in SQL?
7. How do you check if data in 2 columns are the same in SQL?
8. How do I check if two columns have the same value in SQL?
9. How do you check if two tables have the same columns?
10. How do you check if record not exists in SQL?
11. What is drop table if exists?
12. How do you check not exists in SQL?

How do you check if a given data exists in multiple tables?

INSERT INTO $table (`username`, ... ) SELECT $username as `username`, ... FROM DUAL WHERE NOT EXISTS (select username from a where username = $username) AND NOT EXISTS (select username from b where username = $username) AND NOT EXISTS (select username from c where username = $username);

How do I check if two tables have the same data in SQL?

1. Step 1 - Test for Duplicate Rows on TABLEA. If SELECT DISTINCT * FROM TABLEA. ...
2. Step 2 - Test for Duplicate Rows on TABLEB. If SELECT DISTINCT * FROM TABLEB. ...
3. Step 3 - INNER JOIN TABLEA to TABLEB on every column.

How do you check if a value exists in a table SQL?

SQL EXISTS Operator

1. SELECT column_name(s) FROM table_name. WHERE EXISTS. (SELECT column_name FROM table_name WHERE condition);
2. Example. SELECT SupplierName. FROM Suppliers. WHERE EXISTS (SELECT ProductName FROM Products WHERE Products.SupplierID = Suppliers.supplierID AND Price < 20);
3. Example. SELECT SupplierName. FROM Suppliers.

How do you find common data in two tables?

Three options:

1. Use INNER JOIN with DISTINCT SELECT DISTINCT Table1.colA, Table1.colB, Table1.colC FROM Table1 INNER JOIN Table2 ON Table1.colC = Table2.colZ.
2. Use EXISTS SELECT Table1.colA, Table1.colB, Table1.colC FROM Table1 WHERE EXISTS (SELECT 1 FROM Table2 WHERE ColZ = ColC)

How do I check if a stored procedure exists?

Check for stored procedure name using EXISTS condition in T-SQL.

1. IF EXISTS (SELECT * FROM sys.objects WHERE type = 'P' AND name = 'Sp_Exists')
2. DROP PROCEDURE Sp_Exists.
3. go.
4. create PROCEDURE [dbo].[Sp_Exists]
5. @EnrollmentID INT.
6. AS.
7. BEGIN.
8. select * from TblExists.

How do you check if a column exists in SQL?

Colum view to check the existence of column Name in table SampleTable. IF EXISTS ( SELECT * FROM INFORMATION_SCHEMA. COLUMNS WHERE table_name = 'SampleTable' AND column_name = 'Name' ) SELECT 'Column exists in table' AS [Status] ; ELSE SELECT 'Column does not exist in table' AS [Status];

How do you check if data in 2 columns are the same in SQL?

Answer. Yes, within a WHERE clause you can compare the values of two columns. When comparing two columns in a WHERE clause, for each row in the database, it will check the value of each column and compare them.

How do I check if two columns have the same value in SQL?

NULLIF returns the first expression if the two expressions are not equal. If the expressions are equal, NULLIF returns a null value of the type of the first expression. So, above query will return 1 for records in which that columns are equal, the first expression otherwise.

How do you check if two tables have the same columns?

Select Id_pk, col1, col2...,coln from table1 MINUS Select Id_pk, col1, col2...,coln from table2; You can quickly check how many records are having mismatch between two tables. The only drawback with using UNION and MINUS is that the tables must have the same number of columns and the data types must match.

How do you check if record not exists in SQL?

SQL NOT EXISTS

Therefore, the NOT EXISTS operator returns true if the underlying subquery returns no record. However, if a single record is matched by the inner subquery, the NOT EXISTS operator will return false , and the subquery execution can be stopped.

What is drop table if exists?

The DROP TABLE SQL statement enables you to delete a table from the database. ... The DROP TABLE IF EXISTS SQL statement enables a check to see that the table exists prior to attempting the dropping (deletion) of the table. If the table does not exists then the DROP TABLE statement is not executed so no error occurs.

How do you check not exists in SQL?

The SQL NOT EXISTS Operator will act quite opposite to EXISTS Operator. It is used to restrict the number of rows returned by the SELECT Statement. The NOT EXISTS in SQL Server will check the Subquery for rows existence, and if there are no rows then it will return TRUE, otherwise FALSE.