Alright, let's get started. How can we make this query faster? We want the order ID of every order in January and February, 2017. This is the query we've got so far: SELECTorder_idFROMordersWHEREDATEDIFF(orders.
Comprehensive, community-driven list of essential SQL interview questions. Whether you're a candidate or interviewer, these interview questions will help prepare you for your next SQL interview ahead of time.
Indexes are database objects that help improve the performance of theSQL SELECTquery on a table. Typically, an index contains keys built from one or more columns in the table or view. These built keys are stored in a structure (B-tree) in the database server’s physical memory. It enabl...
INSERT emp SELECT 5,2,'Sourabh' SELECT t1.empname [Employee], t2.empname [Manager] FROM emp t1, emp t2 WHERE t1.mgrid = t2.empid Here's an advanced query using a LEFT OUTER JOIN that even returns the employees without managers (super bosses) SELECT t1.empname [Employee], COALESCE...
EXEC (@sqlQuery); Using sp_executesql (Recommended for security & performance): DECLARE @sqlQuery NVARCHAR(MAX) = 'SELECT * FROM Employees WHERE Department = @Dept'; EXEC sp_executesql @sqlQuery, N'@Dept NVARCHAR(50)', @Dept = 'IT'; ...
SQL Job Interview Questions and Answers 1 :: What is SQL (Structured Query Language)? SQL is an English like language consisting of commands to store, retrieve, maintain & regulate access to your database.Read More 2 :: What is the SQL*Plus? SQL*Plus is an application that recognizes &...
query. Q.Whatiscorrelatedsub-query? ACorrelatedsub_queryisasub_querywhichhasreferencetothemain query. Q. What is an Integrity Constraint ? A Integrity constraint is a rule that restricts values to a column in a table. Q. What is Referential Integrity ?
Eventually, in an outer query, apply a WHERE filter and a COUNT() function on the result of the subquery. Solution of SQL Interview Question #3 Solution: SELECT department_name, AVG(salaries.salary) AS avg_salaries FROM employees JOIN salaries ON employees.employee_id = salaries.employee_id ...
9.What is mutating error?(90% asked PL SQL Interview Questions) Answer : It occurs when a trigger tries to update a row that it is currently using. It is fixed by using views or temporary tables, so database selects one and updates the other. ...
4. How to find the query running on a given SPID? 5. What is XACT_ABORT ON? 6. Can we use two CTE’s in a single select query? 7. What are the different join operators in SQL Server? 8. Can we use a table variable inside a nested stored procedure if the table variable created...