The SQL

SQL

SQL is a programming language designed for managing data in relational database management systems ....

 From clause is the source of a rowset to be operated upon in a Data Manipulation Language (DML)

Data Manipulation Language

A data manipulation language is a family of syntax elements similar to a computer programming language used for inserting, deleting and updating data in a database...

 statement. From clauses are very common, and will provide the rowset to be exposed through a Select

Select (SQL)

The SQL SELECT statement returns a result set of records from one or more tables.A SELECT statement retrieves zero or more rows from one or more database tables or database views. In most applications, SELECT is the most commonly used Data Manipulation Language command...

 statement, the source of values in an Update

Update (SQL)

An SQL UPDATE statement changes the data of one or more records in a table. Either all the rows can be updated, or a subset may be chosen using a condition.The UPDATE statement has the following form:...

 statement, and the target rows to be deleted in a Delete

Delete (SQL)

In the database structured query language , the DELETE statement removes one or more records from a table. A subset may be defined for deletion using a condition, otherwise all records are removed.-Usage:The DELETE statement follows the syntax:...

 statement.

FROM is an SQL

SQL

SQL is a programming language designed for managing data in relational database management systems ....

 reserved word in the SQL

SQL:2003

SQL:2003 is the fifth revision of the SQL database query language. The latest revision of the standard is SQL:2008.-Summary:The SQL:2003 standard makes minor modifications to all parts of SQL:1999 , and officially introduces a few new features such as:* XML-related features * Window functions* the...

 standard

The FROM clause is used in conjunction with SQL statements, and takes the following general form:

SQL-DML-Statement
FROM table_name
WHERE predicate

The From clause can generally be anything that returns a rowset, a table, view, function, or system-provided information like the Information Schema

Information Schema

In relational databases, the information schema is an ANSI standard set of read-only views which provide information about all of the tables, views, columns, and procedures in a database...

, which is typically running proprietary commands and returning the information in a table form.

Examples

The following query returns only those rows from table mytable where the value in column mycol is greater than 100.


SELECT *
FROM mytable
WHERE mycol > 100

Requirement

The From clause is technically required in relational algebra and in most scenarios to be useful. However many relational dbms implementations may not require it for selecting a single value, or single row.

SELECT 3.14 AS Pi

Other systems will require a From statement with a keyword, even to select system data.

select to_char(sysdate, 'Dy DD-Mon-YYYY HH24:MI:SS') as "Current Time"
from dual;