## Calculate the difference between results of two count(*) queries based on 2 tables in PostgreSQL

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I want to calculate the difference between the results of 2 `count(*)`-type SELECT queries executed on 2 separate tables of my PostgreSQL database.

This what I'm currently using (however I should be able to wrap it all up into a single SELECT statement):

```SELECT "count"(*) AS val1 FROM tab1;
SELECT "count"(*) AS val2 FROM tab2;
SELECT val2-val1;
```

Try this way:

```select
(
SELECT
"count"(*) as val1
from
tab1
) - (
SELECT
"count"(*) as val2
from
tab2
) as total_count
```

Doing two counts on a single table in a single query, You can use CASE statement for this scenario: SELECT count(*) AS total_agents, SUM(CASE WHEN active = 't' THEN 1 ELSE 0 END) AS active_agents FROM� Count the Number of Rows in Two Tables Using a Single Query There are several ways to simply count the number of rows in two tables using single query. select ( select count(*) from Table1 ) + ( select count(*) from Table2 ) as total_rows from my_one_row_table

```select t1.cnt - t2.cnt
from (select count(*) as cnt from tab1) as t1
cross join (select count(*) as cnt from tab2) as t2
```

PostgreSQL COUNT Function: Counting Rows That Satisfy a , The COUNT() function is an aggregate function that allows you to get the number of If you use the COUNT(*) function on a big table, the query will be slow. Because multiple transactions see different states of data at the same time, there is into groups based on customer id, and use the COUNT() function to count the� To compare two columns and count differences by cells, you can use the Conditional Formatting function to highlight the duplicates first, then use the Filter function to count the total differences. 1. Select the column you want to count the differences, click Home > Conditional Formatting > New Rule. 2.

for same table you can do this.

`select (count(abc)-count(DISTINCT xyz)) from tab;`

How to Calculate Multiple Aggregate Functions in a Single Query , This solution allows for calculating all results in a single query by using 8 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. SELECT. count (*), In PostgreSQL and HSQLDB (and in the SQL standard), there's a special syntax for this. The PIVOT clause can be applied to a table expression to “pivot” it in a� Select COUNT(*) from multiple tables. The following query COUNT the number of rows from two different tables (here we use employees and departments) using COUNT(*) command. SQL Code: SELECT( SELECT COUNT(*) FROM employees ) AS Total_Employees, (SELECT COUNT(*) FROM departments ) AS No_Of_Departments FROM dual Output:

Another option is to use `SUM`:

```SELECT SUM(val) AS result
FROM (SELECT count(*) AS val FROM tab2
UNION ALL
SELECT -count(*) FROM tab1) sub;
```

db<>fiddle demo

My Favorite PostgreSQL Queries and Why They Matter, These sales are represented as tables payment and fake_month for No difference there at all. or appending of two strings, provides a presentation option for results sets. postgres=> SELECT 2|| ' times' || ' 2 equals: ' || 2*2; Determine with COUNT(*) how many records are present before you load up� Imagine you have two different tables/queries that are supposed to have/return identical data. You want to verify this. What's an easy way to show any unmatched rows from each table just like the example below, comparing every column? Assume there are 30 columns in the tables, many of which are NULLable.

Documentation: 9.5: SELECT, SELECT DISTINCT eliminates duplicate rows from the result. When there are multiple queries in the WITH clause, RECURSIVE should be written only These two methods each return a randomly-chosen sample of the table that will Another difference is that these expressions can contain aggregate function calls, � use below piece of query instead. SELECT A.NUM, A.DENOM, cast(A.NUM as float)/cast(A.DENOM as float) FROM ( -- COLUMN SELECTION. TWO NUMBERS WILL REPRESENT A NUM AND A DENOM SELECT (SELECT COUNT(DRG_NO) FROM smsdss.BMH_PLM_PtAcct_V WHERE drg_no IN (061,062,063,064,065,066) AND Adm_Date BETWEEN @SD AND @ED AND PLM_PT_ACCT_TYPE = 'I') AS NUM, (SELECT COUNT(DRG_NO) FROM smsdss.BMH_PLM_PtAcct_V

MySQL Compare Two Tables to Find Unmatched Records, In this tutorial, you will learn how to compare two tables to find unmatched The returned result set is used for the comparison. Second, group the records based on the primary key and columns that need If the values in the columns that need to compare are identical, the COUNT(*) returns 2, See the following query:. You should now see two Connection only queries in the Queries & Connections window pane for Table_A and Table_B. Join Queries With Merge. Now we will combine our queries. Go to the Data tab. Press the Get Data button from the Get & Transform Data section. Choose Combine Queries then Merge from the menu. Now we can setup our merge query.

How to select distinct values from query results in PostgreSQL, DISTINCT is used to remove duplicate rows from the SELECT query and You can use SELECT with DISTINCT on two columns of the table: With GROUP BY and HAVING, you can select distinct values based on group of columns. 1 | abc 2 | xyz 3 | tcs (3 rows) postgres=# select col1, col2,count(*) from� https://www.wiseowl.co.uk - Learn how to use calculations in queries in Microsoft SQL Server. This video teaches you how to create basic calculated columns using simple operators such as add