sql查询如果参数为null则选择全部

Question

I've the following query:

SELECT NAME, SURNAME FROM MY_TABLE WHERE NAME = ?;

Now I want that if '?' is NULL, all records have to be selected. How can I achieve this in SQL? Thanks

Answer 1

Try this:

SELECT * 
FROM MY_TABLE 
WHERE @parameter IS NULL OR NAME = @parameter;

Answer 2

You can also use functions IFNULL , COALESCE , NVL , ISNULL to check null value. It depends on your RDBMS.

MySQL :

SELECT NAME, SURNAME FROM MY_TABLE WHERE NAME = IFNULL(?,NAME);

or

SELECT NAME, SURNAME FROM MY_TABLE WHERE NAME = COALESCE(?,NAME);

ORACLE :

SELECT NAME, SURNAME FROM MY_TABLE WHERE NAME = NVL(?,NAME);

SQL Server / SYBASE :

SELECT NAME, SURNAME FROM MY_TABLE WHERE NAME = ISNULL(?,NAME);

Answer 3

SELECT NAME
FROM MY_TABLE
WHERE NAME LIKE CASE WHEN ? IS NOT NULL THEN ? ELSE '%' END

This will work perfectly but it will return only the not null values.

Answer 4

The foll. query will handle the case where the Name (table column value) can also be NULL:

SELECT NAME, SURNAME FROM MY_TABLE WHERE COALESCE(NAME,'') = COALESCE(?,NAME,'');