What are the three types of results that a subquery can return

What can subqueries return?

A subquery selects and returns values to the first or outer SELECT statement. A subquery can return no value, a single value, or a set of values, as follows: If a subquery returns no value, the query does not return any rows.

Which two types of results can subqueries return?

Types of SQL Subqueries
  • Single Row Subquery. Returns zero or one row in results.
  • Multiple Row Subquery. Returns one or more rows in results.
  • Multiple Column Subqueries. Returns one or more columns.
  • Correlated Subqueries. …
  • Nested Subqueries.

What are the types of sub query?

Types of Subqueries
  • Single Row Sub Query: Sub query which returns single row output. …
  • Multiple row sub query: Sub query returning multiple row output. …
  • Correlated Sub Query: Correlated subqueries depend on data provided by the outer query.

How many types of subquery are there in SQL?

There are three broad types of a subquery in SQL. This chapter from OCA Oracle Database 11g: SQL Fundamentals I Exam Guide explains differences between a single-row subquery, multiple-row subquery and correlated subquery .

What are the four different types of results that can be returned from a subquery?

Subqueries can return different types of information:
  • A scalar subquery returns a single value.
  • A column subquery returns a single column of one or more values.
  • A row subquery returns a single row of one or more values.
  • A table subquery returns a table of one or more rows of one or more columns.

What are subqueries?

A subquery is a query that is nested inside a SELECT , INSERT , UPDATE , or DELETE statement, or inside another subquery.

What are different types of indexes in SQL?

There are two types of Indexes in SQL Server:
  • Clustered Index.
  • Non-Clustered Index.

What are the types of views in SQL?

There are 2 types of Views in SQL: Simple View and Complex View. Simple views can only contain a single base table. Complex views can be constructed on more than one base table.

Can a subquery return multiple columns?

You can write subqueries that return multiple columns. The following example retrieves the order amount with the lowest price, group by agent code.

What are the types of indexes?

Unique indexes enforce the constraint of uniqueness in your index keys.
…
Expression-based indexes efficiently evaluate queries with the indexed expression.
  • Unique and non-unique indexes. …
  • Clustered and non-clustered indexes. …
  • Partitioned and nonpartitioned indexes. …
  • Bidirectional indexes. …
  • Expression-based indexes.

What are different types of indexes in relational database?

There are various types of indexes in SQL server:
  • Clustered Index.
  • Non-Clustered Index.
  • Column Store Index.
  • Filtered Index.
  • Hash Index.
  • Unique Index.

How many types of indexes are there in MySQL?

MySQL has three types of indexes: INDEX, UNIQUE (which requires each row to have a unique value), and PRIMARY KEY (which is just a particular UNIQUE index).
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