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SQL Tutorial

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Selecting data from a table

Syntax:

select field1, field2,...fieldN 
[from table_name1, table_name2...]
[where clause]
[limit [offset M ][limit N]]

When selecting a fixed value, FROM clause is not mandatory.

select 'Hello';
  • select * -> Return all fields
  • select col1, col2 -> Return specified fields
  • offset -> To skip initial records
  • limit -> How many rows to return

SELECT examples:

select * from deptt;
select d.* from deptt d;
select * from deptt d;
select depid, depname, depcity from deptt limit 1;
select depid, depname, depcity from deptt limit 1,2; -- skip 1 and return only 2 rows

Aliases

Tables and Columns can be given alias names for easy readability.

select e.empfname "First Name" from EMP e;

Selecting unique values
Values in columns of a table may repeat across the rows of the table. To get unique values, use select distinct.

select distinct empfname from emp;