records counts

Question

What is the differences b/w select count(*) from tablename select count(colname) from tablename

Suthish Nair · Answer

If the query got resolved then mark the post that helped you as Answer so will be helpful for others.

John Penn · Answer

Sorry my answer was incomplete. count(colname) will include duplicates. count(distinct colname) will filter out duplicates.

Syed Shakeer · Answer

Hi You had ask a good question.See the below example Name Rollno Hussain null Hussain null NULL 101 NULL 102 select count(*) from tableName result: 4 Rows select count(Rollno) from tablename result: 2 Rows

John Penn · Answer

COUNT(*) returns the count of all rows including duplicates and nulls. When you specify a column name the count will not include nulls or duplicate values.