How to set value to null in PostgreSQL?

by giovanny.lueilwitz , in category: PHP Databases , 2 years ago

How to set value to null in PostgreSQL?

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2 answers

Member

by larissa , a year ago

@giovanny.lueilwitz 

To set a value to NULL in PostgreSQL, you can use the NULL keyword. For example:

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UPDATE table_name
SET column_name = NULL
WHERE condition;


This will update the value of column_name in all rows that meet the condition to NULL.


You can also use the NULL keyword to insert a NULL value into a table. For example:

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INSERT INTO table_name (column1, column2, column3)
VALUES (value1, NULL, value3);


This will insert a new row into table_name with value1 in column1, NULL in column2, and value3 in column3.


Keep in mind that NULL is not the same as an empty string ('') or a zero value (0). A NULL value represents an unknown or undefined value, whereas an empty string or a zero value represents a known value.


For more information on NULL values in PostgreSQL, you can refer to the documentation: https://www.postgresql.org/docs/current/sql-expressions.html#SQL-SYNTAX-NULL-HANDLING

by elisha_langworth , 9 months ago

@giovanny.lueilwitz 

In PostgreSQL, to set a value to null, you can use the keyword NULL or the function NULLIF(). Here are two examples of how you can set a value to null:

  1. Using the keyword NULL:
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UPDATE table_name
SET column_name = NULL
WHERE condition;


Replace table_name with the name of your table, column_name with the name of the column you want to set to null, and condition with the appropriate condition to target the specific rows you want to update.

  1. Using the function NULLIF():
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UPDATE table_name
SET column_name = NULLIF(column_name, 'value')
WHERE condition;


Replace table_name with the name of your table, column_name with the name of the column you want to set to null, value with the specific value you want to set to null, and condition with the appropriate condition to target the specific rows you want to update. When the NULLIF() function is used, it sets the value to null if the column value matches the given value.


Remember to execute the appropriate UPDATE statement depending on your specific scenario.