The FROM clause in SQL Server

The SQL Server FROM clause (T-SQL) is used to list the necessary tables in the SQL Server query.

FROM clause clause

 FROM bang1 
[ { INNER JOIN
| LEFT OUTER JOIN
| RIGHT OUTER JOIN
| FULL OUTER JOIN } bang2
ON bang1.cot1 = bang2.cot1 ]

Variable names and variable values

bang1 and bang2 - tables used in SQL statements. Two linked tables according to the principle of state1.cot1 = bang2.cot1.

Note

  1. Must have at least 1 table in the FROM clause.
  2. If there are 2 or more tables, these tables are usually connected by keywords INNER or OUTER. Although it is possible to connect using the old syntax in the WHERE clause, it is recommended to use the new standard with the connection rule in the FROM clause.

Example - 1 table

 SELECT * 
FROM nhanvien
WHERE ten = 'Jane;

This example uses the FROM clause to get the table of nhanvien , no other connection tables.

Example - 2 tables with INNER JOIN

 SELECT nhacungcap.nhacungcap_id, nhacungcap.nhacungcap_ten, donhang.donhang_ngay 
FROM nhacungcap
INNER JOIN donhang
ON nhacungcap.nhacungcap_id = donhang.nhacungcap_id;

In this example, the FROM clause gives 2 tables and donhang , connecting these two tables with INNER JOIN with nhacungcap_id column on both tables.

Example - 2 tables with OUTER JOIN

 SELECT nhanvien.nhanvien_id, danhba.ho 
FROM nhanvien
LEFT OUTER JOIN danhba
ON nhanvien.nhanvien_id = danhba.danhba_id
WHERE nhanvien.ten = 'Sarah';

This FROM clause gives two tables, nhanvien and danhba , using LEFT OUTER JOIN to connect with nhanvien_id column in both tables.

Previous article: SELECT command in SQL Server

Next lesson: Comparison operators in SQL Server

5 ★ | 1 Vote

May be interested

  • HAVING clause in SQLHAVING clause in SQL
    the having clause in sql is used to filter records and retrieve only those records that match the requirements or are actually needed.
  • Interesting Facts About The Santa ClauseInteresting Facts About The Santa Clause
    the santa clause is one of the best christmas movies of all time. however, behind this christmas movie are surprising, little-known facts about the making process.
  • GROUP BY command in SQLGROUP BY command in SQL
    the group by clause in sql is used in conjunction with the select statement to sort data uniformly into groups.
  • ORDER BY command in SQLORDER BY command in SQL
    in sql, the order by clause is used to sort data in ascending order or in descending order on one or more columns.
  • The difference between web server and app serverThe difference between web server and app server
    you have probably seen that the terms web server and app server are often used interchangeably as if they are related to the same thing and also facilitate the website to function properly. but in reality, they are not the same.
  • Network basics: Part 3 - DNS ServerNetwork basics: Part 3 - DNS Server
    a dns server is a server that contains a database of public ip addresses and hostnames associated with them. in most cases, the dns server is used to resolve or translate those common names into ip addresses as required.
  • Sort results in SQLSort results in SQL
    to sort data in sql, we use the order by clause.
  • The clause combines UNION data in SQLThe clause combines UNION data in SQL
    in sql, you can combine the same structured data from multiple tables into one query using the union and union all operators.
  • How to set up your own Git server on LinuxHow to set up your own Git server on Linux
    while you can count on globally renowned git hosting services like github, in some cases it is better to host a personal git server for enhanced privacy, customizability, and security.
  • Use IIS to set up FTP Server on WindowsUse IIS to set up FTP Server on Windows
    set up an ftp server (file transfer protocol server) to share and convert large files with unlimited traffic.