How do you create a yes/no boolean field in SQL server?

问题:

What is the best practice for creating a yes/no Boolean field when converting from an access database or in general?

回答1:

The equivalent is a bit field.

In SQL you use 0 and 1 to set a bit field (just as a yes/no field in Access). In Management Studio it displays as a false/true value (at least in recent versions).

When accessing the database through ASP.NET it will expose the field as a boolean value.

回答2:

The BIT datatype is generally used to store boolean values (0 for false, 1 for true).

回答3:

You can use the bit column type.

回答4:

You can use the data type bit

Values inserted which are greater than 0 will be stored as '1'

Values inserted which are less than 0 will be stored as '1'

Values inserted as '0' will be stored as '0'

This holds true for MS SQL Server 2012 Express

回答5:

You can use the BIT field.

For adding a BIT column to an existing table, the SQL command would look like:

ALTER TABLE table_name ADD yes_no BIT

If you want to create a new table, you could do: CREATE TABLE table_name (yes_no BIT).

回答6:

Sample usage while creating a table:

[ColumnName]     BIT   NULL   DEFAULT 0 

回答7:

bit will be the simplest and also takes up the least space. Not very verbose compared to "Y/N" but I am fine with it.

回答8:

There are already answers saying use of Bit. I will add more to these answers.

You should use bit for representing Boolean values.

Remarks from MSDN article.

Bit can take a value of 1, 0, or NULL.

The SQL Server Database Engine optimizes storage of bit columns. If there are 8 or less bit columns in a table, the columns are stored as 1 byte. If there are from 9 up to 16 bit columns, the columns are stored as 2 bytes, and so on.

The string values TRUE and FALSE can be converted to bit values: TRUE is converted to 1 and FALSE is converted to 0.

Converting to bit promotes any nonzero value to 1.

Note: It is good practice to keep values as 1 and 0 only with data type NOT NULL

As Bit have values 1, 0 and NULL. See truth table for this. So plan values accordingly. It might add confusion by allowing NULL value for bit data type.

References 1 2

回答9:

You can use the BIT field

To create new table:

CREATE TABLE Tb_Table1 ( ID              INT, BitColumn       BIT DEFAULT 1 ) 

Adding Column in existing Table:

ALTER TABLE Tb_Table1 ADD BitColumn  BIT DEFAULT 1 

To Insert record:

INSERT Tb_Table1 VALUES(11,0) 

回答10:

bit is the most suitable option. Otherwise I once used int for that purpose. 1 for true & 0 for false.

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