带有搜索Web应用程序可选字段的SQL查询

Question

Not an SQL expert:

I am currently implementing a Searching Web Application. The user will send a GET request to a particular Endpoint .

The Endpoint will accept a set of URL Params and the request can come with optional fields. Such as 1, 2 or 3 fields.

My Database table for USER looks like this.

+--------------+---------+------+-----+---------+----------------+
| id        | firstName    | lastName | email | zip | phone      |
+--------------+---------+------+-----+---------+----------------+

Now the web application will get a GET Request with either Phone or Zip or Email .

I have two solutions for doing this but both look bad:

Solution 1:

1. Have multiple SQL Queries and Execute them according to the URL Params, I receive.

   Select * from User where phone=1111111111 and zip=12345 and email=test@email.com;

   Select * from User where phone=1111111111 and zip=12345;

   ... ...

And so on........I will end up having many queries and this will be a bad implementation. Also will be bad to maintain.

Solution 2:

Other solution that I am thinking of is to have a method, which will build an SQL query based on the URL Params I receive.

Example:

buildSQLQuery(phone,zip,email){

String sql = "Select * from User where "

if(phone!=null  && email!=null && zip!=null ){
sql = sql   + "phone = " + phone + " and zip = " + zip + " and email = " + email;
}else if (phone!=null  && email!=null && zip==null){
sql = sql + "phone = " + phone + " and email = " + email;
}
.......
......
And so on have all conditions and build that particular query.
}

I don't like both these solutions.

Is there a way to write a Single SQL query and that will handle all the above conditions.

Something like if the URL Param value is NULL then that should not affect the query and I will get my expected results.

As in my case the optional values, which don't come in are set to NULL .

Can I implement something like this?

Select * from User where (if notNull (phone))(phone = phone ) and (if notNull (email))(email = email ) and (if notNull (zip))(zip = zip )

If any of the above one value is null then don't use that part in where Condition .

Also I will always have one field present, so there will be no case where all values are null.

I am implementing this web application in Java and Spring MVC. If anyone can guide me in the correct direction.

Thank you.

Answer 1

I think one more possible solution like:

String sql = "Select * from User where 1=1 "

    if(phone!=null){
    sql +=  " and phone = " + phone ;}

    if(email!=null){
    sql +=  " and email = " + email ;}

    if(zip!=null){
    sql +=  " and zip = " + zip ;}

OR You can try following single query:

select * from User 
where (@phone is null OR phone = @phone) AND (@email is null OR email = @email) AND (@zip is null OR zip = @zip)

Answer 2

You can do like this:

SELECT * FROM User where(
   IF($phone != 0, IF(phone = $phone,1,0), 0) AND 
   IF($email != 0, IF(email = $email,1,0),0) AND 
   IF($zip != 0, IF(zip = $zip,1,0),0)
)

assumed for PHP you can change the syntax, may be this query not do the job completely but if you provide fiddle i will modify this to give the proper result.