Questions tagged [alter-table]

SQL statement used to alter an existing table object.

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Why can't you add an Identity to an existing colum in SQL Server?

What is so special about an Identity column? I am pretty sure there is a valid reason, but I'm trying to get a better understanding of SQL. So what is so special about an Identity column that this can'...
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1answer
20 views

Suppressing SELECT output before \gexec?

This answer is great for when I needed to reown 150 tables, each with 40 tables, but displays the 6000 rows from SELECT before running the 6000 ALTER statements. Thus, as stated in the Subject, is ...
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1answer
32 views

Improving remake of primary key performance

I'm using a MySQL 5.7 hosted on AWS that has a table with about 500,000,000 rows and 124GB in size. I want to drop the existing primary key (id) and create a new composite primary key of 2 columns: ...
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1answer
61 views

Why do my RDS read IOPS drop after a certain period of time?

I am trying to add non-null constraints on several columns in a table with about 70,000,000 rows. Each statement is just ALTER TABLE table_name ALTER COLUMN column_name SET NOT NULL;, and each ...
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1answer
35 views

Change bucket count for Primary Key Nonclustered Hash on existing In-Memory table

I'm on SQL Server 2019 Enterprise edition. I have a table with this definition CREATE TABLE dbo.MyMemoryTable ( FirstId int NOT NULL, SecondId int NOT NULL, MyCount int NOT NULL, ...
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Snowflake: Creating a table with a column name which is ANSI reserved fails, but adding a column(alter table) same ANSI reserved column name succeeds

CREATE TABLE test_table (LOCALTIMESTAMP varchar(10)) This query fails with .invalid column definition name 'LOCALTIMESTAMP' (ANSI reserved) ALTER TABLE test_table ADD COLUMN LOCALTIMESTAMP varchar(...
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2answers
242 views

“Alter Table” modify multiple columns vs multiple Alter table single column in INNODB?

I am updating collations of my database tables and columns from utf8bin to utf8mb4_bin. Engine is INNODB with file per table enabled. I used a query to generate identify all utf8 columns from ...
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2answers
45 views

How to add generated column to db2 table?

I've got a table with the following: Columns: --- URL [nullable, e.g. "https://dba.stackexchange.com/"] APPFK [nullable, e.g. 654654] LINKTYPE ["Page", "Link", or "...
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1answer
16 views

Why am I getting an error if I am trying to modify data type? [closed]

I am facing an error when I passed the following syntax in MySQL: ALTER TABLE store MODIFY (DOB char(40)) ; I am attaching a screenshot too because then you can see that the column DOB is having all ...
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1answer
80 views

Why a dropped index is still there, and does it prevent a table from being altered?

I have a column (named RequestDate) which I need to change from NULL to NOT NULL, but there's a clustered index on that column, so I first need to drop that index. Originally, the index was created ...
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2answers
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In mysql, how to add a primary key and a composite key to a table so that it forbids duplicate rows, when there are null values within the columns?

In the following table (8 mi rows), every column has Null values. However, there can never be two identical rows (there will be always at least one column with a different value for each row). How can ...
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1answer
56 views

How do you change the storage parameters of a already made table (sql developer)?

Summarize the problem I have been given 6 tables that have all been created already and I was told to change the storage parameters of those tables. the issue I run into is that I can only change ...
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1answer
31 views

alter table alter column causes huge log and data file growth

I have a table with 2.6B rows in it and I need to change a column from Char(1) to Varchar(64). the table is over 300GB with a few indexes. The column in nullable, so the transaction i'm running is: ...
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2answers
33 views

Promote MySQL Table Partition to Table

My Google Searching skills were not enough to find a solution to this. If possible, how can I promote a partition on a table to a table on its own? Let's assume I have part0, part1, and part2. Is ...
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1answer
37 views

SQL Server :: how to move country code column to another table?

I have 2 tables: tbl_Countries: 250 values, with columns like CountryName (Afghanistan), TwoCharCountryCode (AF), ThreeCharCountryCode (AFG). Like this: CountryName TwoCharCountryCode ...
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1answer
40 views

Why is ALTER faster than UPDATE (for full table rewrites)?

Let's create a garbage table.. CREATE TABLE foo AS SELECT x::text FROM generate_series(1,20e6) AS t(x); Time: 14077.654 ms (00:14.078) Now, let's look at boring UPDATE, UPDATE foo SET x = 'foo'; ...
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1answer
22 views

How to insert '1001-01-01 00:00:00' into MariaDB when altering a table?

I created a table in HeidiSQL: CREATE TABLE `publish_dt` ( `ID` BIGINT(20) NOT NULL AUTO_INCREMENT, `TS` DATETIME NULL DEFAULT NULL, `Text` VARCHAR(50) NOT NULL COLLATE 'utf8mb4_unicode_ci'...
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1answer
268 views

Alter column fails due to “hidden” statistic

I'm trying to change a column data type from datetime2 to datetimeoffset. I have db owner permissions. Whenever I run the query: alter table dbo.<my-table> alter column [TimeStamp] ...
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1answer
246 views

MySQL Store Procedure - Setting AUTO_INCREMENT value

I am in trouble coding a store procedure as shown below CREATE DEFINER=`dbcomexuser`@`%` PROCEDURE `clearance_imp`(IN CAPIfilename VARCHAR(12)) BEGIN DECLARE `_rollback` BOOL DEFAULT 0; DECLARE ...
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1answer
299 views

Why is ADD CONSTRAINT … NOT VALID taking a long time?

I added NOT NULL constraints to some columns like this, expecting the command to be very fast because of NOT VALID. However, it took about 60-100 seconds, and seemed to lock the table for the whole ...
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1answer
32 views

Specific format/formula when changing column datatype [duplicate]

Can one modify a column's datatype using a very specific conversion format? For example, when converting from datetime to varchar I'd like to use the yyyy-MM-dd hh:mm:ss format, not the system ...
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2answers
107 views

MySQL: change column type using expression

In a MySQL database, I need to convert some UUID columns (BINARY(16)) into VARCHAR. I want to convert them in the canonical form, not as bytes. For clarity, in lowercase and with hyphens, and not in ...
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2answers
519 views

How can I set a column to NOT NULL without locking the table during a table scan?

(former question was: Will Postgres use a multi-column index when setting multiple colums not null?) Typically, when I set a column not null, if it doesn't have an index then I add it first, so that ...
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0answers
51 views

Altering big table with gh-ost on Google Cloud

We need to add some indexes and one additional column to a large MySQL table. MySQL is Google Cloud SQL version 5.7.25-google-log. Some table info: currently holding 1 331 363 322 rows size of the ...
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3answers
159 views

How to calculate end_date from start_date and duration in SQL Server Query

I have a table with 4 fields .Start-date, Duration, End_date, Actual_date. I am providing the start_date and duration as the input to calculate end-date. While calculating the end_date the ...
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25 views

Check constraint on grouped conditions

Take the following table as an example: GroupID AlphaID BetaID 1 0 1 1 1 1 1 2 2 2 0 1 2 1 2 ...
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1answer
69 views

How to fix conversion error from InnoDB to MyISAM?

How can I fix conversion error from InnoDB to MyISAM for these tables? MariaDB [db_name]> ALTER TABLE wp_posts ENGINE = MyISAM; ERROR 1071 (42000): Specified key was too long; max key length is ...
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1answer
22 views

Atler Table Alter Column Set Default FALSE: Why my alter table took 10 minutes to finish?

I have run the following command and it took about 10 minutes to finish: ALTER TABLE "bookings" ALTER COLUMN "local_direct_booking" SET DEFAULT FALSE for a table bookings which had 111.834 rows (...
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1answer
115 views

MySql Error #1054 when adding new column to table using prepared statement

I'm trying to add a new column named lot to a table, but I'm getting error #1054 - Unknown column 'lot' in 'field list'. What could be the problem? Here's the query: SET @lot = (SELECT lot_no_start ...
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24 views

Adding a column and new foreign key constraint in one line

Let's say we have a table called Salesman with the folling properties Create Table SalesMan( EmplyeeId int Primary Key, Name varchar(20) Not Null, LastName Varchar(20) Not Null, Email Varchar(...
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32 views

Alter Table operations blocks replication in MySQL

We are using Amazon Web Service's MySQL 5.7.26 with 4 read-only replicas. After some Alter Table operations we have found that the replication stops working. The symtoms are great replica lag that is ...
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1answer
51 views

Does “alter table … set data type” functionally differ from “alter table … type”?

The docs show [SET DATA] TYPE which implies the SET DATA part is optional, but the 9.1 release notes also imply that SET DATA TYPE may be different: Allow ALTER TABLE ... SET DATA TYPE to avoid ...
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1answer
250 views

ALTER fixed-length COLUMN on compressed table

I wonder if compression of a table actually changes ALTER TABLE rules. I found no information on this topic. Let's consider a simple example. I'll create a table and alter one of the columns from INT ...
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1answer
89 views

Alter on huge table consumes all disk space

I'm running MySQL 8 on Ubuntu 19. I have a table that is 543G and I have to add a new column and index. I've started with the new column: alter table hugeTable add column newCol tinyint(1) after ...
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33 views

ALTER TABLE query to convert table to utf8mb4_bin takes many hours - how to optimise this?

I have a table which has approx 15 million rows - I won't add the schema here but it has 96 columns (far too many in my opinion). The current table collation is latin1_swedish_ci but for full emoji ...
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1answer
232 views

Prevent drop column with index on it in PostgreSQL

In PostgreSQL when you drop column in a table, all indexes and constraints which use this column will be also dropped silently. If you overlook such situation, you can get serious problems in ...
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0answers
272 views

Dynamic script to alter a column type having an index

I am writing a script to update the datatype of a column in SQL Server on a list of tables, if the existing column are not yet of the desired type. The column should be converted from a VARCHAR to a ...
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1answer
445 views

Drop multiple columns at the same time from a SQL Server table

I am currently looking some way to delete multiple columns at the same time from a given table in sql server. One way of doing that is to use ALTER statement as shown below: Alter Table [USER_DB].[...
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1answer
44 views

SQL Server - Migration script testing - Refresh table definition manually without dropping it

How can a table definition be manually refreshed without also manually crafting a bunch of ALTER TABLE statements, or dropping and recreating the table? This is normally handled by the publish ...
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4answers
560 views

Fast alter column NVARCHAR(4000) to NVARCHAR(260)

I have a performance problem with very large memory grants handling this table with a couple of NVARCHAR(4000) columns. Thing is these columns are never larger than NVARCHAR(260). Using ALTER TABLE [...
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1answer
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what happen you using put the ALTER statement in a transaction.?

I got a question about "What happens when you using Alter table command when a database is running? is it possible to run the alter table when database is running? and if it's possible what will ...
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1answer
379 views

Alter table add column with no default blocks

tl;dr The following query blocks the postgres server when executed ALTER TABLE "image_data" ADD COLUMN "user_status" varchar(30) NULL engine version 10.6 # of rows 1.5 mils Hi, I have a somewhat ...
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0answers
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What is the order of execution of alter operations in an alter query in MySQL?

Consider the following queries CREATE TABLE MyTable (f2 INT); ALTER TABLE MyTable ADD COLUMN f1 INT, DROP COLUMN f1; In the above query drop column seems to happen before add column and query fails....
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1answer
2k views

Entity Framework 6: How can I add new column to existing table and at the same time update view (add column) in same migration file [closed]

Example in the EF6 migration file Up method. I wish to add a new column B in existing table Country. Sql("ALTER TABLE [dbo].[Country] ADD [B] INT DEFAULT((0)) NOT NULL;") Then I will need to ...
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1answer
22 views

Altering Tables using Tablenames from other Table

I have a database with several tables and i have a table which contains all tablenames which I want to alter. I want to perform a query like this: ALTER TABLE (SELECT "TABLE_NAME" FROM "...
2
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2answers
635 views

Db2 REORGCHK returns the SQL2310N (Error “-668”) message

I have a Db2 database on my Linux laptop. The database is not heavily loaded. I access it from time to time for the development purposes. I removed a column: db2 "alter table SCHEMA.TABLE drop ...
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214 views

Possibility of using self-referential foreign key to create hierarchical comments

I am an accidental DBA and have a question regarding the table structure of a website I maintain (postgresql 9.6 backend). Imagine a typical content website (let's call it 'Links'), where users post ...
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1answer
2k views

Is ALTER TABLE … DROP COLUMN really a metadata only operation?

I've found several sources that state ALTER TABLE ... DROP COLUMN is a meta-data only operation. Source How can this be? Does the data during a DROP COLUMN not need to be purged from the underlying ...
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1answer
148 views

Change column datatype without rewrite when data remains unchanged

For example: timestamp(tz) to int8 date to int4 json to text The raw data is unchanged, and the only difference is how that data is handled. So it should be possible to change back and forth cleanly ...
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1answer
2k views

SQLServer add a default value for a column [closed]

I am using MS SQL Server. I have an "action" table with an "action_type" column that I want to set a default value of "to do" for. My DDL in MS SQL Studio errors! I have read many many articles trying ...

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