How SQL query gets executed?

How is SQL query executed?

Query Process Steps

  1. Getting Data (From, Join)
  2. Row Filter (Where)
  3. Grouping (Group by)
  4. Group Filter (Having)
  5. Return Expressions (Select)
  6. Order & Paging (Order by & Limit / Offset)

How MySQL query execute?

Query execution is not that complicated. MySQL simply follows its plan, fetching rows from each table in order and joining based on the relevant columns. Along the way, it may need to create a temporary table to store the results. Once all the rows are available, it sends them to the client.

How will you execute a query?

Run the query

  1. Locate the query in the Navigation Pane.
  2. Do one of the following: Double-click the query you want to run. Click the query you want to run, and then press ENTER.

How do I start a query in MySQL?

Some of the commonly used MySQL queries, operators, and functions are as follows :

  1. SHOW DATABASES. This displays information of all the existing databases in the server. …
  2. USE database_name. database_name : name of the database. …
  3. DESCRIBE table_name. …
  4. SHOW TABLES. …
  5. SHOW CREATE TABLE table_name. …
  6. SELECT NOW() …
  7. SELECT 2 + 4; …
  8. Comments.

What is MySQL query plan?

A query on a huge table can be performed without reading all the rows; a join involving several tables can be performed without comparing every combination of rows. The set of operations that the optimizer chooses to perform the most efficient query is called the “query execution plan”, also known as the EXPLAIN plan.

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How SQL query works internally in MySQL?

SQL Query mainly works in three phases .

  1. 1) Row filtering – Phase 1: Row filtering – phase 1 are done by FROM, WHERE , GROUP BY , HAVING clause.
  2. 2) Column filtering: Columns are filtered by SELECT clause.
  3. 3) Row filtering – Phase 2: Row filtering – phase 2 are done by DISTINCT , ORDER BY , LIMIT clause.

What are the SQL clauses?

SQL clauses

  • CONSTRAINT clause.
  • FOR UPDATE clause.
  • FROM clause.
  • GROUP BY clause.
  • HAVING clause.
  • ORDER BY clause.
  • The result offset and fetch first clauses.
  • USING clause.

What is offset in SQL query?

SQL | OFFSET-FETCH Clause

  • OFFSET.
  • The OFFSET argument is used to identify the starting point to return rows from a result set. Basically, it exclude the first set of records. Note:
  • FETCH.
  • The FETCH argument is used to return a set of number of rows. FETCH can’t be used itself, it is used in conjuction with OFFSET. Syntax:

In which sequence SQL query is executed?

Six Operations to Order: SELECT, FROM, WHERE, GROUP BY, HAVING, and ORDER BY. By using examples, we will explain the execution order of the six most common operations or pieces in an SQL query. Because the database executes query components in a specific order, it’s helpful for the developer to know this order.