Table A has columns 1 and 2.
Column 1's value must be unique if column 2 is equal to x.
ALTER TABLE A
ADD UNIQUE (1) WHERE 2 = x.
But this gives me a syntax error near WHERE.
I tried to create an index, but I can't figure out how to make that do what I want either.
Create unique nonclustered index [my_index]
on [TableA]([1])
where [2] = x
Here's an alternative solution using a Function although the index is a better solution:
CREATE FUNCTION dbo.CheckConstraint
(
#col1 int,
#col2 CHAR(1)
)
RETURNS INT
AS
BEGIN
DECLARE #ret INT
SELECT #ret = COUNT(*)
FROM YourTable
WHERE col1 = #col1 AND #col2 = 'X'
RETURN #ret
END;
CREATE TABLE YourTable (col1 int, col2 char(1));
ALTER TABLE YourTable
ADD CONSTRAINT CheckForXConstraint CHECK (NOT (dbo.CheckConstraint(col1,col2) > 1));
INSERT INTO YourTable VALUES (1, 'X');
INSERT INTO YourTable VALUES (2, 'X');
INSERT INTO YourTable VALUES (2, 'Y');
INSERT INTO YourTable VALUES (2, 'X'); <-- This line fails
SQL Fiddle Demo
Related
declare #temp table
(
Id int,
Qty int
)
insert into #temp values(1,null)
update #temp set Qty+=2
select * from #temp
I am trying to update the Qty column however the Qty column is null by default. So because the production database column might be null when I try to update I am getting a null value I need Qty to be 2.
Use coalesce (or isnull) to handle the null case.
update #temp set Qty = coalesce(Qty,0) + 2;
If you want to increment the value, then the column should not allow NULLs.
I would suggest that you default the value to 0. Then don't insert a NULL value explicitly:
declare #temp table (
Id int,
Qty int not null default 0
);
insert into #temp (id) values (1);
update #temp set Qty += 2;
select * from #temp;
You can also express the insert as:
insert into #temp (id, value) values (1, default);
At times I need to store a temporary value to a field. I have a stored procedure that adds it using:
Insert new record first then
SELECT #Record_Value = SCOPE_IDENTITY();
UPDATE ADMIN_Publication_JSON
SET NonPubID = CAST(#Record_Value as nvarchar(20)) + '_tmp'
WHERE RecID = #Record_Value
It simply takes the identity value and adds an '_tmp' to the end. Is there a way that I can create a default value in the table that would do that automatically if I did not insert a value into that field?
The NonPubID column is just a NVARCHAR(50).
Thanks
You could write a trigger, that replaces NULL with that string upon INSERT.
CREATE TRIGGER admin_publication_json_bi
ON admin_publication_json
AFTER INSERT
AS
BEGIN
SET NOCOUNT ON;
UPDATE apj
SET apj.nonpubid = concat(convert(varchar(20), i.id), '_tmp')
FROM admin_publication_json apj
INNER JOIN inserted i
ON i.id = apj.id
WHERE i.nonpubid IS NULL;
END;
db<>fiddle
Downside: You cannot explicitly insert NULLs for that column, should that be desired.
Check out NewKey col below:
CREATE TABLE #Table
(
ID INT NOT NULL IDENTITY(1,1) PRIMARY KEY CLUSTERED,
IDValue VARCHAR(1) ,
ModifiedDT DATETIME NULL,
NewKey AS ( CONVERT(VARCHAR(100),ID)+'_Tmp' )
)
INSERT #Table( IDValue, ModifiedDT )
SELECT 'A', GETDATE()
UNION ALL
SELECT 'Y', GETDATE() - 1
UNION ALL
SELECT 'N', GETDATE() - 5
SELECT * FROM #Table
create table sample(id int primary key,name varchar(100))
insert into sample values(1,'a')
,(2,'a')
,(3,'d')
,(4,'b')
,(5,'b')
--insert into sample values(6,'a'),(7,'b')
this record is not allow to insert the table.it disply error
Easiest solution is to check the table if the value being inserted is already present in the table twice before the insert statement.
--Preparation
DECLARE #sample TABLE
(
id INT IDENTITY PRIMARY KEY --USE IDENTITY to auto increment your primary key
,name VARCHAR(100)
)
--Initial Values
INSERT INTO #sample
VALUES
('a')
,('a')
,('d')
,('b')
,('b')
DECLARE #name VARCHAR(100)
SET #name = 'a'
IF(SELECT COUNT(id) FROM #sample WHERE name = #name) <= 1
BEGIN
INSERT INTO #sample
VALUES (#name)
END
ELSE
BEGIN
SELECT 'Error: Name ''' + #name + ''' already exists twice. Only two same values are allowed in name field!'
END
DECLARE #ID INT
SET #ID = (select top 1 USER_REQ_JOB_ID
from T8504_USER_REQ_JOB
where JOB_GRP_ID = 160
order by LST_UPDT_TS desc)
SELECT INPUT_PARM_VAL_TX
from TBL_RPT_JOB_INPUT_PARAM
where USER_REQ_JOB_ID = #ID
This returns these results:
USA
USCC
6
7
2
These five records what I get I want to assign to five different variables to use in stored procedure.
I was trying with table variable like this :
declare #CID table (
Region Char(3)
,Segment Char(3)
,MasterContractId int
,ctcid int
,templateid int)
insert into #CID (Region,Segment,MasterContractId,ctcid,templateid)
But how to insert that 5 rows here?
INSERT INTO #CID
select * from
(
select
'Temp' + convert(char(1), row_number() over (order by (select 0))) as columnName,
INPUT_PARM_VAL_TX as Value
from TBL_RPT_JOB_INPUT_PARAM where USER_REQ_JOB_ID = #ID
) d
pivot
(
max(value)
for columnname in (Temp1, Temp2, Temp3, Temp4, Temp5)
) piv;
See if this helps.
Take a look at this fiddle for an example.
Courtesy:
Add row number to this T-SQL query
Efficiently convert rows to columns in sql server
EDIT: The sql adds an extra column to generate row numbers to use it as an extra column, which is pivoted as column heading.
it's really gross, but one way you could probably do it is this (though you'll need to apply it to your case):
http://sqlfiddle.com/#!6/d41d8/21507
declare #table TABLE (value varchar(50))
INSERT INTO #table
VALUES ('first')
INSERT INTO #table
VALUES ('second')
INSERT INTO #table
VALUES (3)
INSERT INTO #table
VALUES (4)
DECLARE #temp TABLE (id int identity(1,1), value varchar(50))
INSERT INTO #temp
SELECT [value]
FROM #table t
SELECT *
FROM #temp
DECLARE #CID TABLE (Region varchar(50), cont varchar(50), another int, andAnother int)
INSERT INTO #CID
(
Region,
cont,
another,
andAnother
)
VALUES
(
(SELECT value FROM #temp WHERE id = 1), -- Region - varchar
(SELECT value FROM #temp WHERE id = 2), -- cont - varchar
(SELECT value FROM #temp WHERE id = 3), -- another - int
(SELECT value FROM #temp WHERE id = 4) -- andAnother - int
)
SELECT * FROM #cid
note that i assumed you're using mssql, you did not specify
Is it possible to create a Database which has 1 column (but not the column of primary key) to be auto-increment? So that when I insert value to the database, i don't need to fill in the value myself, and DB will fill in that value for that column for me (and increment every time I do a new insert)?
Thank you.
Yes, of course it is possible. Just make this column a unique key (not a primary key) and it has to be declared with a special attribute: "IDENTITY" for SQL Server, and
"AUTO_INCREMENT" for MySQL (see the example below) . And another column can be a primary key.
On MySQL database the table could be declared like this:
CREATE TABLE `mytable` (
`Name` VARCHAR(50) NOT NULL,
`My_autoincrement_column` INTEGER(11) NOT NULL AUTO_INCREMENT,
PRIMARY KEY (`Name`),
UNIQUE KEY `My_autoincrement_column` (`My_autoincrement_column`)
);
Yes, you can do this. Here is a sample for SQL Server using IDENTITY:
CREATE TABLE MyTable (
PrimaryKey varchar(10) PRIMARY KEY,
IdentityColumn int IDENTITY(1,1) NOT NULL,
DefaultColumn CHAR(1) NOT NULL DEFAULT ('N')
)
INSERT INTO MyTable (PrimaryKey) VALUES ('A')
INSERT INTO MyTable (PrimaryKey) VALUES ('B')
INSERT INTO MyTable (PrimaryKey, DefaultColumn) VALUES ('C', 'Y')
INSERT INTO MyTable (PrimaryKey, DefaultColumn) VALUES ('D', 'Y')
INSERT INTO MyTable (PrimaryKey, DefaultColumn) VALUES ('E', DEFAULT)
--INSERT INTO MyTable (PrimaryKey, DefaultColumn) VALUES ('F', NULL) -- ERROR
--> Cannot insert the value NULL into column 'DefaultColumn', table 'tempdb.dbo.MyTable'; column does not allow nulls. INSERT fails.
SELECT * FROM MyTable
Here is an example using SQL Server using functions to roll-your-own incrementing column. This is by means not fault tolerant or the way I would do it. (I'd use the identity feature.) However, it is good to know that you can use functions to return default values.
DROP TABLE MyTable
GO
DROP FUNCTION get_default_for_mytable
GO
CREATE FUNCTION get_default_for_mytable
()
RETURNS INT
AS
BEGIN
-- Declare the return variable here
DECLARE #ResultVar int
-- Add the T-SQL statements to compute the return value here
SET #ResultVar = COALESCE((SELECT MAX(HomeBrewedIdentityColumn) FROM MyTable),0) + 1
-- Return the result of the function
RETURN #ResultVar
END
GO
CREATE TABLE MyTable (
PrimaryKey varchar(10) PRIMARY KEY,
IdentityColumn int IDENTITY(1,1) NOT NULL,
DefaultColumn CHAR(1) NOT NULL DEFAULT ('N'),
HomeBrewedIdentityColumn int NOT NULL DEFAULT(dbo.get_default_for_mytable())
)
GO
INSERT INTO MyTable (PrimaryKey) VALUES ('A')
INSERT INTO MyTable (PrimaryKey) VALUES ('B')
INSERT INTO MyTable (PrimaryKey, DefaultColumn) VALUES ('C', 'Y')
INSERT INTO MyTable (PrimaryKey, DefaultColumn) VALUES ('D', 'Y')
INSERT INTO MyTable (PrimaryKey, DefaultColumn) VALUES ('E', DEFAULT)
--INSERT INTO MyTable (PrimaryKey, DefaultColumn) VALUES ('F', NULL) -- ERRROR
--> Cannot insert the value NULL into column 'DefaultColumn', table 'tempdb.dbo.MyTable'; column does not allow nulls. INSERT fails.
SELECT * FROM MyTable
Results
PrimaryKey IdentityColumn DefaultColumn HomeBrewedIdentityColumn
---------- -------------- ------------- ------------------------
A 1 N 1
B 2 N 2
C 3 Y 3
D 4 Y 4
E 5 N 5
I think you can have only 1 identity autoincrement column per table, this columns doesn't have to be the primary key but it would mean you have to insert the primary key yourself.
If you already have a primary key which is auto increment then I would try and use this if possible.
If you are trying to get an row ID to range on for querying then I would look at creating a view which has the row ID in it (not SQL 2000 or below).
Could you add in what your primary key is and what you intend to use the auto increment column for and it might help come up with a solution
On sql server this is called an identity column
Oracle and DB2 have sequence but I think you are looking for identity and all major dbms (mysql, sql server, db2, oracle) support it.