I am trying to change the column size from 100 to 150 varchar data type using following query:
alter table data_warehouse.tbl_abc
alter column first_nm varchar(150) null;
Getting the following error:
SQL Error [42601]: ERROR: syntax error at or near "varchar"
Position: 77
The syntax is a bit different, so try this:
ALTER TABLE data_warehouse.tbl_abc
ALTER COLUMN first_nm type varchar(120);
The error in your syntax is that you missed a TYPE keyword:
ALTER TABLE data_warehouse.tbl_abc
ALTER COLUMN first_nm TYPE varchar(150);
and if you have a NOT NULL constraint you want to remove, add a new ALTER COLUMN inside the same ALTER TABLE statement:
ALTER TABLE data_warehouse.tbl_abc
ALTER COLUMN first_nm TYPE varchar(150),
ALTER COLUMN first_nm DROP NOT NULL;
for reference look here: https://www.postgresql.org/docs/current/sql-altertable.html
Edit: as in the comment, if you have a view which involves the same column, drop it and re-create it under transaction:
BEGIN TRANSACTION;
DROP VIEW [...];
ALTER TABLE [...];
CREATE VIEW [...];
COMMIT;
Be aware that to alter a table, you must acquire an exclusive lock on it, so during the whole process, all the queries over the same table and on the views of the table are locked, also if they don't read from the altered column (because the whole table is locked) - use with caution in production environment
Related
I want to alter the existing column Site_SiteId in SQL Server to make it as not null with default value 1 but getting a syntax error:
ALTER TABLE dbo.ImagingEvents
ALTER COLUMN Site_SiteId bit NOT NULL DEFAULT 1
default is a constraint so you need to add it to the table:
ALTER TABLE dbo.ImagingEvents ADD DEFAULT 1 FOR Site_SiteId
First you need to ALTER the column:
ALTER TABLE dbo.ImagingEvents ALTER COLUMN Site_SiteId bit NOT NULL;
Note that if you have any rows that already have the value NULL you will need to UPDATE them first, before performing the ALTER.
Then, personally, I would recommend creating a named constraint, like so:
ALTER TABLE dbo.ImagingEvents ADD CONSTRAINT DF_Site_SiteId DEFAULT 1 FOR Site_SiteId;
Having named constraints, rather than the automatically named ones, is far better for transferable code.
I am trying to do this:
ALTER TABLE CompanyTransactions DROP COLUMN Created
But I get this:
Msg 5074, Level 16, State 1, Line 2
The object 'DF__CompanyTr__Creat__0CDAE408' is dependent on column 'Created'.
Msg 4922, Level 16, State 9, Line 2
ALTER TABLE DROP COLUMN Created failed because one or more objects access this column.
This is a code first table. Somehow the migrations have become all messed up and I am trying to manually roll back some changed.
I have no idea what this is:
DF__CompanyTr__Creat__0CDAE408
You must remove the constraints from the column before removing the column. The name you are referencing is a default constraint.
e.g.
alter table CompanyTransactions drop constraint [df__CompanyTr__Creat__0cdae408];
alter table CompanyTransactions drop column [Created];
The #SqlZim's answer is correct but just to explain why this possibly have happened. I've had similar issue and this was caused by very innocent thing: adding default value to a column
ALTER TABLE MySchema.MyTable ADD
MyColumn int DEFAULT NULL;
But in the realm of MS SQL Server a default value on a colum is a CONSTRAINT. And like every constraint it has an identifier. And you cannot drop a column if it is used in a CONSTRAINT.
So what you can actually do avoid this kind of problems is always give your default constraints a explicit name, for example:
ALTER TABLE MySchema.MyTable ADD
MyColumn int NULL,
CONSTRAINT DF_MyTable_MyColumn DEFAULT NULL FOR MyColumn;
You'll still have to drop the constraint before dropping the column, but you will at least know its name up front.
As already written in answers you need to drop constraints (created automatically by sql) related to all columns that you are trying to delete.
Perform followings steps to do the needful.
Get Name of all Constraints using sp_helpconstraint which is a system stored procedure utility - execute following exec sp_helpconstraint '<your table name>'
Once you get the name of the constraint then copy that constraint name and execute next statement i.e alter table <your_table_name>
drop constraint <constraint_name_that_you_copied_in_1> (It'll be something like this only or similar format)
Once you delete the constraint then you can delete 1 or more columns by using conventional method i.e Alter table <YourTableName> Drop column column1, column2 etc
When you alter column datatype you need to change constraint key for every database
alter table CompanyTransactions drop constraint [df__CompanyTr__Creat__0cdae408];
You need to do a few things:
You first need to check if the constrain exits in the information schema
then you need to query by joining the sys.default_constraints and sys.columns
if the columns and default_constraints have the same object ids
When you join in step 2, you would get the constraint name from default_constraints. You drop that constraint. Here is an example of one such drops I did.
-- 1. Remove constraint and drop column
IF EXISTS(SELECT *
FROM INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_NAME = N'TABLE_NAME'
AND COLUMN_NAME = N'LOWER_LIMIT')
BEGIN
DECLARE #sql NVARCHAR(MAX)
WHILE 1=1
BEGIN
SELECT TOP 1 #sql = N'alter table [TABLE_NAME] drop constraint ['+dc.name+N']'
FROM sys.default_constraints dc
JOIN sys.columns c
ON c.default_object_id = dc.object_id
WHERE dc.parent_object_id = OBJECT_ID('[TABLE_NAME]') AND c.name = N'LOWER_LIMIT'
IF ##ROWCOUNT = 0
BEGIN
PRINT 'DELETED Constraint on column LOWER_LIMIT'
BREAK
END
EXEC (#sql)
END;
ALTER TABLE TABLE_NAME DROP COLUMN LOWER_LIMIT;
PRINT 'DELETED column LOWER_LIMIT'
END
ELSE
PRINT 'Column LOWER_LIMIT does not exist'
GO
In addition to accepted answer, if you're using Entity Migrations for updating database, you should add this line at the beggining of the Up() function in your migration file:
Sql("alter table dbo.CompanyTransactions drop constraint [df__CompanyTr__Creat__0cdae408];");
You can find the constraint name in the error at nuget packet manager console which starts with FK_dbo.
I had the same problem and this was the script that worked for me with a table with a two part name separated by a period ".".
USE [DATABASENAME]
GO
ALTER TABLE [TableNamePart1].[TableNamePart2] DROP CONSTRAINT [DF__ TableNamePart1D__ColumnName__5AEE82B9]
GO
ALTER TABLE [TableNamePart1].[ TableNamePart1] DROP COLUMN [ColumnName]
GO
I needed to replace an INT primary key with a Guid. After a few failed attempts, the EF code below worked for me. If you hyst set the defaultValue... you end up with a single Guid a the key for existing records.
protected override void Up(MigrationBuilder migrationBuilder)
{
migrationBuilder.DropUniqueConstraint("PK_Payments", "Payments");
migrationBuilder.DropColumn(
name: "PaymentId",
table: "Payments");
migrationBuilder.AddColumn<Guid>(
name: "PaymentId",
table: "Payments",
type: "uniqueidentifier",
defaultValueSql: "NewId()",
nullable: false);
}
Copy the default constraint name from the error message and type it in the same way as the column you want to delete.
I had the same problem, I could not remove migrations, it would show error that something is already applied, so i changed my DB name in appsettings, removed all migrations, and then added new migration and it worked. Dont understand issue completely, but it worked
I fixed by Adding Dropping constraint inside migration.
migrationBuilder.DropForeignKey(
name: "FK_XX",
table: "TableX").
and below recreates constraint.
migrationBuilder.AddForeignKey(
name: "FK_XX",
table: "TableX",
column: "ColumnX",
onDelete: ReferentialAction.Restrict);
I am trying to alter a column in my ingres DB to expand the size of the column.
The query i'm running is
ALTER TABLE test_table ALTER COLUMN address varchar(100) NOT NULL
Which gives error
Error: ALTER TABLE: invalid change of attributes on an ALTER COLUMN
SQLState: 42000 ErrorCode: 3859
Anyone any idea why I'm getting this error? I've checked the syntax for altering tables.
Probably you have NULL in data. Update your table first (set to empty string or any value you want):
LiveDemo
UPDATE test_table
SET address = '' -- or another value indicating missing addres like 'none'
WHERE address IS NULL;
And then try:
ALTER TABLE test_table ALTER COLUMN address varchar(100) NOT NULL;
EDIT:
If you don't want to enforce NOT NULL use just:
LiveDemo2
ALTER TABLE test_table ALTER COLUMN address varchar(100);
I'm trying to alter the table of an access database. I keep getting a syntax error for something I think should be pretty simple.
Here is what I tried to do and the error I am getting.
yes you have syntax error as what access tells you, try this one
ALTER TABLE EMP_2 ADD COLUMN EMP_PCT NUMBER(4);
ALTER TABLE EMP_2 ADD COLUMN PROJ_NUM CHAR(3);
the syntax
ALTER TABLE table {ADD {COLUMN field type[(size)] [NOT NULL] [CONSTRAINT index] |
ALTER COLUMN field type[(size)] |
CONSTRAINT multifieldindex} |
DROP {COLUMN field I CONSTRAINT indexname}}
ALTER TABLE statement
I want to alter a table column to be nullable. I have used:
ALTER TABLE Merchant_Pending_Functions Modify NumberOfLocations NULL
This gives an error at Modify. What is the correct syntax?
Assuming SQL Server (based on your previous questions):
ALTER TABLE Merchant_Pending_Functions ALTER COLUMN NumberOfLocations INT NULL
Replace INT with your actual datatype.
If this was MySQL syntax, the type would have been missing, as some other responses point out.
Correct MySQL syntax would have been:
ALTER TABLE Merchant_Pending_Functions MODIFY NumberOfLocations INT NULL
Posting here for clarity to MySQL users.
In PostgresQL it is:
ALTER TABLE tableName ALTER COLUMN columnName DROP NOT NULL;
for Oracle Database 10g users:
alter table mytable modify(mycolumn null);
You get "ORA-01735: invalid ALTER TABLE option" when you try otherwise
ALTER TABLE mytable ALTER COLUMN mycolumn DROP NOT NULL;
Although I don't know what RDBMS you are using, you probably need to give the whole column specification, not just say that you now want it to be nullable. For example, if it's currently INT NOT NULL, you should issue ALTER TABLE Merchant_Pending_Functions Modify NumberOfLocations INT.
As others have observed, the precise syntax for the command varies across different flavours of DBMS. The syntax you use works in Oracle:
SQL> desc MACAddresses
Name Null? Type
----------------------------------------- -------- ----------------------------
COMPUTER NUMBER
MACADDRESS VARCHAR2(12)
CORRECTED_MACADDRESS NOT NULL VARCHAR2(17)
SQL> alter table MACAddresses
2 modify corrected_MACAddress null
3 /
Table altered.
SQL> desc MACAddresses
Name Null? Type
----------------------------------------- -------- ----------------------------
COMPUTER NUMBER
MACADDRESS VARCHAR2(12)
CORRECTED_MACADDRESS VARCHAR2(17)
SQL>
For SQL Server or TSQL
ALTER TABLE Complaint.HelplineReturn ALTER COLUMN IsDisposed BIT NULL
This depends on what SQL Engine you are using, in Sybase your command works fine:
ALTER TABLE Merchant_Pending_Functions
Modify NumberOfLocations NULL;
For HSQLDB:
ALTER TABLE tableName ALTER COLUMN columnName SET NULL;
ALTER TABLE Merchant_Pending_Functions MODIFY COLUMN `NumberOfLocations` INT null;
This will work for you.
If you want to change a not null column to allow null, no need to include not null clause. Because default columns get not null.
ALTER TABLE Merchant_Pending_Functions MODIFY COLUMN `NumberOfLocations` INT;
Oracle
ALTER TABLE Merchant_Pending_Functions MODIFY([column] NOT NULL);
SQLite
The ALTER TABLE command is a bit special. There is no possibility to modify a column. You have to create a new column, migrate the data, and then drop the column:
-- 1. First rename
ALTER TABLE
Merchant_Pending_Functions
RENAME COLUMN
NumberOfLocations
TO
NumberOfLocations_old
-- 2. Create new column
ALTER TABLE
Merchant_Pending_Functions
ADD COLUMN
NumberOfLocations INT NULL
-- 3. Migrate data - you need to write code for that
-- 4. Drop the old column
ALTER TABLE
Merchant_Pending_Functions
DROP COLUMN
NumberOfLocations_old
Make sure you add the data_type of the column to modify.
ALTER TABLE TABLE_NAME MODIFY COLUMN_NAME DATA_TYPE NULL;