How to find unique key 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

1 vote186 views1 answer
Mysql dump specific tables
SQL
0 vote179 views1 answer
Select place default lat long
SQL
-1 vote168 views1 answer
Ssms connect with connection string
SQL
9 votes190 views6 answers
Check constraint in sql
SQL
1 vote178 views1 answer
Failed to stop mysqld.service: Unit mysqld.service not loaded.
SQL
0 vote188 views1 answer
Select into table variable
SQL
6 votes178 views2 answers
Mysql first day of month
SQL
0 vote169 views1 answer
Access refused mysql xampp server
SQL
0 vote162 views1 answer
Sql clear table
SQL
0 vote166 views1 answer
1 column values in to 1 single row in sql
SQL