SQL Server count number of distinct values in each column of a table

Question

I have a table with ~150 columns. I\'d like to find the count(distinct(colName)) for each column but am wondering if there\'s a way to do so without actually t

Answer 1

You can do this:

DECLARE @query varchar(max)
    SELECT @query = 
    'SELECT ' + SUBSTRING((SELECT ',' +'COUNT(DISTINCT(' + column_name + ')) 
             As ' + column_name + ' '  
             FROM information_schema.columns
             WHERE 
             table_name = 'table_name'
             for xml path('')),2,200000)  +  'FROM table_name'

PRINT(@query)

Answer 2

I don't believe this is possible with just MySQL. I would think your going to have to use a server side language to get the results you want.

Use "DESC TABLE" as your first query and then for each "field" row, compile your query.

---

Ignore this, wrong system tag :)

Answer 3

This should do:

select count(*) from (select distinct * from myTable) as t

Here is SQL Fiddle test.

create table Data
(
    Id int,
    Data varchar(50)
)

insert into Data 
select 1, 'ABC'
union all
select 1, 'ABC'

select count(*) 
from (select distinct * from Data) as t

Answer 4

Expanded answer from Bryan. His great answer lists the fields alphabetically.
This is no problem if you have a dozen fields or so. If you have 150 fields, like OP stated, this keeps the fields in their table's order.
I modified his query in order to examine a 213 column (vendor's) table and wanted to post for future reference.

DECLARE @Table SYSNAME = 'Your table name; without schema; no square brackets'; 

-- REVERSE and STUFF used to remove trailing UNION in string
SELECT REVERSE(STUFF(REVERSE((SELECT 'SELECT ' 
        + CAST(column_id AS VarChar(4)) + ' AS [column_id],' -- extra column
        + '''' + name 
        + ''' AS [Column], COUNT(DISTINCT(' 
        + QUOTENAME(name) + ')) AS [Count] FROM ' 
        + QUOTENAME(@Table) + ' UNION ' 
    -- get column name from sys.columns  
    FROM   sys.columns 
    WHERE  system_type_id NOT IN (34,240) AND object_id = Object_id(@Table) 
    ORDER BY column_id -- keeps columns in table order
    -- concatenate result strings with FOR XML PATH
    FOR XML PATH (''))), 1, 7, ';'));

I decided to not edit Bryan's answer because often people won't need the extra column.
(The ORDER BY has no effect if you don't add the column_id column. I believe this is because only the outermost ORDER BY is guarenteed to order the final output; I'd love to have a msft reference that confirms this)

EDIT: Using function Count with field types Image and Geography throws error.
Added "system_type_id NOT IN (34,240)".

Answer 5

Use the below script to build T-SQL query that will return a distinct count of each column in a table. Replace @Table value with your table name.

DECLARE @Table SYSNAME = 'TableName'; 

-- REVERSE and STUFF used to remove trailing UNION in string
SELECT REVERSE(STUFF(REVERSE((SELECT 'SELECT ''' + name 
                                     + ''' AS [Column], COUNT(DISTINCT(' 
                                     + QUOTENAME(name) + ')) AS [Count] FROM ' 
                                     + QUOTENAME(@Table) + ' UNION ' 
                              -- get column name from sys.columns  
                              FROM   sys.columns 
                              WHERE  object_id = Object_id(@Table)
                              -- concatenate result strings with FOR XML PATH
                              FOR XML PATH (''))), 1, 7, ';'));