How to find unique element in sql

DISTINCT
- select distinct * from employees; ==> 
           retrieves any row if it has at 
           least a single unique column.
- select distinct first_name from employees; ==> 
              retrieves unique names
              from table. (removes duplicates)
- select distinct count(*) from employees;
          retrieve number of unique rows
          if any row has at least a single unique data.

Similar codes

0 vote154 views1 answer
Drop database using terminal postgres
SQL
1 vote133 views1 answer
"i_am_a_dummy flag" in MySQL
SQL
1 vote138 views1 answer
Found option without preceding group in config file: /etc/mysql/mariadb.conf.d/50-server.cnf at line: 1
SQL
3 votes160 views2 answers
MySQL query to get column names
SQL
10 votes134 views4 answers
Primary key in sql
SQL
1 vote133 views2 answers
Into sql
SQL
6 votes136 views2 answers
Find mysql version linux
SQL
10 votes149 views2 answers
Show tables in schema oracle
SQL
-2 votes139 views3 answers
Oracle tablespace usage
SQL
0 vote134 views1 answer
Mysql isshow
SQL