How to insert an empty line to SQL table?

Utilizing DEFAULT VALUES

When your table contains an auto-increment ID or columns with predefined defaults, leveraging DEFAULT VALUES simplifies the insertion of an empty line. This method circumvents syntax errors when having an auto-increment-only column, without needing to explicitly mention NULL:

CREATE TABLE AutoIncrementTable (
    ID int NOT NULL PRIMARY KEY AUTO_INCREMENT -- "NULL Values Welcome Here!", says Auto-incrementing ID
);
-- "Oh look! An empty row for fresh auto-increment value to call home"
INSERT INTO AutoIncrementTable DEFAULT_VALUES;
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For tables with multiple columns lacking defaults, you need to list them out and provide NULL or a default value for each:

-- "Behold! A Table with not one but two columns!"
CREATE TABLE MultiColTable (
    ID int NOT NULL PRIMARY KEY AUTO_INCREMENT,
    Col1 varchar(255),
    Col2 int
);
-- "Placeholder? We don't need no sticking placeholder!"
INSERT INTO MultiColTable (Col1, Col2) VALUES (NULL, NULL);
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Rapid dummy data insertion

If you need to insert multiple empty rows for setting up your database or testing purposes, you can use loops or generation scripts:

DECLARE @i int = 0;
-- Loading up the insert cannon! Firing in 3, 2, 1...
WHILE @i < 10
BEGIN
    INSERT INTO YourTable DEFAULT_VALUES;
    SET @i = @i + 1;
END;
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Heads up! The above example inserts 10 empty rows, tweak the number to fit your needs.

Know your table, know your command

In tables devoid of any auto-increment columns, you'll need to detail NULL for each column or provide an empty string ('') if the column is a varchar and it's not nullable:

INSERT INTO NoAutoIncrementTable (varcharCol, intCol) VALUES ('', NULL);
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Be aware, when dealing with tables that have constraints like foreign keys or NOT NULL in place, inserting empty or NULL values might not be possible without violating those conditions.

Understand the reasons

An empty row in a database signifies so much more than nothingness. It could symbolize an absence, a placeholder for future data, or act as a separator. Additionally, remember that these empty rows use storage space and exist in database index structures, making it important to deliberate their purpose and impact.

Spot the trigger

Adjust your strategy when working in a database where audits or triggers are tied to inserts. Inadvertently, you might stumble upon some unintended results. Consider disabling triggers temporarily or introducing conditions to handle it:

-- "Triggers off!" says SQL table
ALTER TABLE YourTable DISABLE TRIGGER ALL;
INSERT INTO YourTable DEFAULT_VALUES;
-- "Triggers on!" says SQL table, ready for action!
ALTER TABLE YourTable ENABLE TRIGGER ALL;
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Bulk operations and specific patterns

For bulk operations, consider using INSERT INTO...SELECT from a dummy table or a table value constructor if you're dealing with specific data patterns:

-- "Clone Army coming right up!" - SQL Commander
WITH EmptyRows(N) AS (
    SELECT 1 UNION ALL SELECT N + 1 FROM EmptyRows WHERE N < 1000
)
-- "Voila!" - Empty row Magician!
INSERT INTO YourTable DEFAULT_VALUES
SELECT N FROM EmptyRows OPTION (MAXRECURSION 1000);
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