Dataset

Create dataset Alter schema set options Drop dataset

Tables

Create table Create table as select Create table like Create table copy Create table options Create external table Create temp table Alter column drop not null Alter column set options Alter column change datatype Alter table set options Alter table rename Alter table add column Alter table drop column Drop temp table Drop table Drop external table

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Create Snapshot table List of snapshots Restore snapshot table Copy to Snapshot table Drop snapshot table

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Create view Create Materialized view Alter view set options Alter materialized view options Drop view Drop materialized view

Routines

Create Stored Procedure Create Function Create row access policy Create table function Drop function Drop table function Drop Procedure Drop row access policy

DML

INSERT values INSERT from a table INSERT values with subquery UPDATE statement UPDATE from table MERGE Statement DELETE statement TRUNCATE table

Home » Bigquery » Tutorials » Alter column change datatype

BigQuery Alter column change datatype

To change the data type of a column in a table in BigQuery to a less restrictive data type. For example, a NUMERIC data type can be changed to a BIGNUMERIC type but not the reverse

Alter column change datatype example

The following example changes the data type of column col1 from an INT64 to NUMERIC:

ALTER TABLE dataset.table ALTER COLUMN col1 SET DATA TYPE NUMERIC;

Explanation

You can also coerce data types from more restrictive to less restrictive parameterized data types. For example, you can increase the maximum length of a string type or increase the precision or scale of a numeric type.

For example

NUMERIC(6,10) to NUMERIC(8,12)
NUMERIC to BIGNUMERIC(40, 20)
STRING(5) to STRING(7)

Syntax reference

ALTER TABLE [IF EXISTS] table_name
ALTER COLUMN [IF EXISTS] column_name SET DATA TYPE data_type