How to select data in the SQL

Selecting Data

The select statement is used to query the database and retrieve selected data that match the criteria that you specify. Here is the format of a simple select statement:

select "column11"
  [,"column12",etc] 
  from "tablename"
  [where "condition"];
  [] = optional

The column names that follow the select keyword determine which columns will be returned in the results. You can select as many column names that you'd like, or you can use a "*" to select all columns.

The table name that follows the keyword from specifies the table that will be queried to retrieve the desired results.

The where clause (optional) specifies which data values or rows will be returned or displayed, based on the criteria described after the keyword where.

Conditional selections used in the where clause:

=	Equal
>	Greater than
<	Less than
>=	Greater than or equal
<=	Less than or equal
<>	Not equal to
LIKE	*See note below

The LIKE pattern matching operator can also be used in the conditional selection of the where clause. Like is a very powerful operator that allows you to select only rows that are "like" what you specify. The percent sign "%" can be used as a wild card to match any possible character that might appear before or after the characters specified.

 For example:

select first, last, city
   from empinfo
   where first LIKE 'Pu%';

This SQL statement will match any first names that start with 'Pu'. Strings must be in single quotes.

Or you can specify,

select first, last
   from empinfo
   where last LIKE '%d';

This statement will match any last names that end in a 'd'.

select * from empinfo
   where first = 'Pune';

This will only select rows where the first name equals 'Pune' exactly.

Sample Table: empinfo
first	last	id	age	city	state
John	sons	90901	45	Delhi	Delhi
Mary	coms	90902	25	Punjab	Punjab
Eric	wards	80801	32	Pune	Maharastra
Mary Com	Edwards	80802	32	hyderabad	Telangana
Ginger	well	90802	42	Chennai	Tamilanadu
Sebastian	Wala	98001	23	Goa	Goa
Gussa	Gray	20802	35	Banglore	Karnataka
Mary Com	May	30802	52	Mumbai	Maharastra
Erisca	Williams	32427	60	Noida	Haryana
Lebroy	Lable	34243	22	Luknow	UP
Emma	Clever	33343	22	Kolkata	Bengal

Try the below sample select statements at home.

select first, last, city from empinfo; 

select last, city, age from empinfo
       where age > 30; 

select first, last, city, state from empinfo
       where first LIKE 'S%'; 

select * from empinfo; 

select first, last, from empinfo
       where last LIKE '%s'; 

select first, last, age from empinfo
       where last LIKE '%ary%'; 

select * from empinfo where first = 'Erisc';