- How do I count null values in PostgreSQL?
- Can we use two group by in same query?
- How do I round up in postgresql?
- What is the equivalent of Rowid in Postgres?
- What is Rownum equivalent in Postgres?
- How do I count the number of columns in PostgreSQL?
- How do I sum in PostgreSQL?
- How do I find the Postgres row number?
- What is the data type for percentage in SQL?
- Does Count ignore NULL values?
- How do you count null values?
- How do I calculate percentage in PostgreSQL?
- Can I use where and having together?
- How can calculate percentage?
- Can I use Row_number in where clause?
- How do you count without group by?
- How do I count rows in SQL without counting?
- Does Avg ignore null values?

## How do I count null values in PostgreSQL?

Use count(*) : select count(*) from train where “column” is NULL; count() with any other argument counts the non-NULL values, so there are none if “column” is NULL .

Some workaround when you want to count the values on aggregations, including NULL ones, but can’t use count(*) (if other columns are different too)..

## Can we use two group by in same query?

type can be only either debit or credit and instrument can be any method like credit card etc. What I need is to get a query which select year, month,type, instrument and the sum of ‘amount’ grouped by type and instrument as well as sum of income grouped by year and month.

## How do I round up in postgresql?

Put another way, “Take our number, round up, and make it an integer.” If Postgres SQL had an INTEGER function, CEILING could be mimic’d like so: INTEGER(ROUND(x,1)). FLOOR() : ThiS function rounds the decimal up to the next higher integer. The decimal is eliminated when the number is rounded up to an integer.

## What is the equivalent of Rowid in Postgres?

PostgreSQL does not have the ROWID pseudocolumn found in Oracle. However, the ctid field can definitely be treated as an equivalent of ROWID in the PostgreSQL database. The ctid field is a field that exists in every PostgreSQL table.

## What is Rownum equivalent in Postgres?

Postgresql does not have an equivalent of Oracle’s ROWNUM. In many cases you can achieve the same result by using LIMIT and OFFSET in your query.

## How do I count the number of columns in PostgreSQL?

PostgreSQL COUNT SELECT SELECT COUNT ( [*], [DISTINCT] [column_name] ) FROM TABLE_NAME; Let’s dig a little deeper into the syntax shown above: SELECT – This is used to select certain columns from the database. COUNT – This is used to count the number of records in this table.

## How do I sum in PostgreSQL?

Use the SUM() function to calculate the sum of values. Use the DISTINCT option to calculate the sum of distinct values. Use the SUM() function with the GROUP BY clause to calculate the sum for each group.

## How do I find the Postgres row number?

How to Get Row Number in PostgreSQL using ROW_NUMBER() Since PostgreSQL 8.4, you can easily show row number in PostgreSQL using ROW_NUMBER() function. Here’s the SQL query to get row id in PostgreSQL. In the above SQL query, we use row_number() window function to generate row number for each row.

## What is the data type for percentage in SQL?

You should use decimal(p,s) in 99.9% of cases. Percent is only a presentation concept: 10% is still 0.1. Simply choose precision and scale for the highest expected values/desired decimal places when expressed as real numbers.

## Does Count ignore NULL values?

COUNT(expression) does not count NULL values. It can optionally count or not count duplicate field values. COUNT always returns data type BIGINT with xDBC length 8, precision 19, and scale 0. COUNT(*) returns the count of the number of rows in the table as an integer.

## How do you count null values?

Using SELECT COUNT(*) or SELECT COUNT(1) (which is what I prefer to use) will return the total of all records returned in the result set regardless of NULL values. Using COUNT()will count the number of non-NULL items in the specified column (NULL fields will be ignored).

## How do I calculate percentage in PostgreSQL?

Calculating the “percentage of the total” for each row with Postgres can be done with a window function: SELECT *, (value / SUM(value) OVER ()) AS “% of total” FROM transactions WHERE quarter = ‘2015-03-31’ and company_id = 1; We’re using “OVER ()”, which means the sum over all rows returned by the where clause.

## Can I use where and having together?

A query can contain both a WHERE clause and a HAVING clause. … The HAVING clause is then applied to the rows in the result set. Only the groups that meet the HAVING conditions appear in the query output. You can apply a HAVING clause only to columns that also appear in the GROUP BY clause or in an aggregate function.

## How can calculate percentage?

1. How to calculate percentage of a number. Use the percentage formula: P% * X = YConvert the problem to an equation using the percentage formula: P% * X = Y.P is 10%, X is 150, so the equation is 10% * 150 = Y.Convert 10% to a decimal by removing the percent sign and dividing by 100: 10/100 = 0.10.More items…

## Can I use Row_number in where clause?

One can use row_number function in where clause in SQL server by Common Table Expression (CTE) as shown in the image below.

## How do you count without group by?

The OVER clause lets us execute the COUNT function without the need for a group by and in the above example it will return the count of all records returned in the query.

## How do I count rows in SQL without counting?

Count Rows of a table Without using Count() FunctionSELECT so.[name] as., CASE WHEN si. indid between 1 and 254.THEN si.[name] ELSE NULL END.AS [Index Name], si. indid, rows.FROM sys. sysindexes si.INNER JOIN sysobjects so.ON si. id = so. id.More items…•

## Does Avg ignore null values?

The value of the AVG function is always a floating point value or a NULL value. The AVG function only returns a NULL value if and only if all values in the group are NULL values.