Tally Table

Technical Article

Create a Tally Function (fnTally)

  • Script

Many people have published high performance, read-less, Inline Table Valued functions that use Itzik Ben-Gan's wonderful "Virtual Numbers Table" to replace WHILE loops and other forms of RBAR. This one is Jeff Moden's version.

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2019-08-13 (first published: )

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SQLServerCentral Article

Tally OH! An Improved SQL 8K “CSV Splitter” Function

  • Article

The Tally Table has proven to be a simple and elegant method for avoiding many varieties of RBAR. Unfortunately, one of its more common uses, that of a CSV splitter, has a well-known and serious performance problem. MVP Jeff Moden shows us what that problem is and how to correct it. (UPDATED with additional info and attachments on 5/12/2011).

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2012-12-28 (first published: )

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Question of the Day

Fun with JSON II

I have some data in a table:

CREATE TABLE #test_data
(
    id INT PRIMARY KEY,
    name VARCHAR(100),
    birth_date DATE
);

-- Step 2: Insert rows  
INSERT INTO #test_data
VALUES
(1, 'Olivia', '2025-01-05'),
(2, 'Emma', '2025-03-02'),
(3, 'Liam', '2025-11-15'),
(4, 'Noah', '2025-12-22');
If I run this query, how many rows are returned?
SELECT t1.[key] AS row,
       t2.*
FROM OPENJSON(
     (
         SELECT t.* FROM #test_data AS t FOR JSON PATH
     )
             ) t1
    CROSS APPLY OPENJSON(t1.value) t2;

See possible answers