How do I make a column not unique in SQL Server?

How do I make a column not unique in SQL Server?

1. Go to the table in context, where you want to make the modification.
2. Click on the “Structure” tab (mostly next to Browse)
3. Look for the “+Indexes” link, just under the columns. Yeah… now click it.
4. Now you can see all the “Indexes” and you can now click on the “DROP” button or link to modify.

How do I change unique index to non-unique in SQL Server?

There’s no way to alter a non-unique index to be unique. Remember that a unique index is a form of constraint. You’re saying that there can only be one row for each set of values in the column list. In the general case, this requires you to use clean the data before you can apply the constraint.

How do you display non-unique values in SQL?

How to Find Duplicate Values in SQL

1. Using the GROUP BY clause to group all rows by the target column(s) – i.e. the column(s) you want to check for duplicate values on.
2. Using the COUNT function in the HAVING clause to check if any of the groups have more than 1 entry; those would be the duplicate values.

How do you modify unique constraints?

To modify a unique constraint

1. In the Object Explorer, right-click the table containing the unique constraint and select Design.
2. On the Table Designer menu, click Indexes/Keys….
3. In the Indexes/Keys dialog box, under Selected Primary/Unique Key or Index, select the constraint you wish to edit.

How do I find non distinct rows in SQL?

1. select count(distinct NAME) from MYTABLE.
2. SELECT * FROM MYTABLE WHERE NAME IN(SELECT NAME FROM MYTABLE GROUP BY NAME HAVING COUNT(*) =1)
3. SELECT * FROM MYTABLE WHERE NAME IN(SELECT NAME FROM MYTABLE GROUP BY NAME HAVING COUNT(*) >1)

How do I create unique key in SQL Server?

Open SQL Server Management Studio. Right click your Table, click “Design”. Right click the column you want to edit, a popup menu appears, click Indexes/ Keys . Click the “Add” Button. Expand the “General” tab. Make sure you have the column you want to make unique selected in the “columns” box. Change the “Type” box to ” Unique Key “. Click “Close”.

What is a SQL Server constraint?

Constraints in SQL Server are predefined rules and restrictions that are enforced in a single column or multiple columns, regarding the values allowed in the columns, to maintain the integrity, accuracy, and reliability of that column’s data. In other words, if the inserted data meets the constraint rule, it will be inserted successfully.

What is unique in SQL Server?

In SQL Server the unique key has the following characteristics: There can be multiple unique keys defined on a table. Unique Keys result in NONCLUSTERED Unique Indexes by default. One or more columns make up a unique key. Column may be NULL, but on one NULL per column is allowed. A unique constraint can be referenced by a Foreign Key Constraint.

What is unique key in SQL Server?

Unique Key in SQL. A unique key is a set of one or more than one fields/columns of a table that uniquely identify a record in a database table. You can say that it is little like primary key but it can accept only one null value and it cannot have duplicate values. The unique key and primary key both provide a guarantee for uniqueness…