INSERT INTO Customers (CustomerID, Name, CustomerNum, Payment_purpose, Amount) VALUES ('1', 'Nikhil', '21', 'Rent', '4000') The table have fields CustomerID, Name, Payment_purpose, CustomerNum, Amount.ĬREATE TABLE Customers ( CustomerID int NOT NULL PRIMARY KEY, Name varchar(255), CustomerNum int, Payment_purpose varchar(255), Amount int ) Īnd also inserting some data sample as follows: Let us prepare a demo data database table named Customer having information about customers and payment amount. Types of MySQL Subqueryįollowing are the types of Subquery with syntaxes and examples: 1. We can say that when we run this query then the query inside outer executes first and the result returned by it is used as an input for outer query. Then the outer query selects all the names from PersonDb table who work in PersonIT whose PersonID is matched from the result set of the inner query. In the above SQL Statement, first of all, the subquery returns all the PersonID of PersonIT located in city Delhi. SELECT PersonName FROM PersonDb WHERE PersonID IN (SELECT PersonID FROM PersonIT WHERE City=’Delhi’) Suppose, we have the following SQL query which provides us the persons who work in IT sector located in Delhi. In MySQL, we can write Subquery anywhere where expression SQL query is used but it is surrounded within parenthesis.
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Let us explain to you how to use the MySQL Subquery to write any compound queries and also learn the correlated Subquery concept. Hence, the main use of Subquery can be to compute an instant value for another query to be executed. But JOINS returns rows and Subquery returns either a single value as a result set or a row set. Thus, like JOINS, a Subquery is used to combine table data from different tables into a single result set. So, here MySQL looks outside the subquery and finds tablename1 in the outer query. SELECT * FROM tablename1 WHERE column1 = ANY (SELECT column1 FROM tablename2 WHERE tablename2……). This query could not be bounded in a set function. We can say that a Subquery or Inner Query is a SQL query that can be used as a condition for main SQL query outside that helps to restrict the data rows to be fetched from the tables embedded within the WHERE clause.
Single Row Subquery: It either returns zero or a single row.
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