How do I write a complex query in SQL?

Question

How to build complex queries using dbForge Studio for SQL Server Open Query Builder. . Add tables to the query. . Create a subquery. . Create JOINs between the tables. . Build WHERE or HAVING clause. . Create GROUP BY or ORDER BY clause. . View and execute the query. . Analyze the result.

What are examples of complex SQL queries?

Complex SQL Queries Examples(90% ASKED IN Interviews)Query to find Second Highest Salary of Employee?(click for explaination) ... Query to find duplicate rows in table?(click here for explaination ) ... How to fetch monthly Salary of Employee if annual salary is given?(click here for Explaination)

What is a complex query?

DEFINITION: A complex query is a parameter query that searches using more than one parameter value i.e. on two or more criteria.

How do you read a complex SQL query?

How to Understand Long and Complex SQL Queries1STEP 1) Big Picture First! ... 2STEP 2) Focus on the Final Columns First! ... 3STEP 3) Understand the Final GROUP BY and WHERE Clauses. ... 4STEP 4) Look at the Final JOINs. ... 5STEP 5) Look at CTEs and Subqueries in Reverse Order. ... 6STEP 6) Time to Understand CTEs and Subqueries.

How do you write a good SQL query?

1Provide Correct Formatting for the Query. ... 2Specify the SELECT fields instead of using SELECT * ... 3Remove Correlated Subqueries if not required. ... 4Limit the results obtained by the query. ... 5Remove The DISTINCT Clause if not required. ... 6Avoid Functions in Predicates. ... 7Avoid OR, AND, NOT operators if possible.

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