please correct me with the sql query

Whats wrong wrong with this query please correct me on this syntactcally it's going wrong please correct me on this how to concatenate this

string cmd = "SELECT * 
                FROM [tbl_students] 
               WHER开发者_开发知识库E course_id=@courseId 
                 AND branch_id IN ("+branchId+") 
                 AND (@passoutYear is null or passout_year>=@passoutYear) 
                 AND (@currentBacklog is null or current_backlog<=@currentBacklog)
                 AND gender=@sex 
                 AND (@eGap is null or gapin_education<=@egap)
                 AND (@firstYrPercent is null or first_yea_percent>=@firstYrPercent
                 AND (@secondYrpercent is null or second_year_percent>=@secondYrPercent)
                 AND (@thirdYrPercent is null or third_year_percent>=@thirdYrPercent)
                 AND (@finalYrpercent is null or final_year_percent>=@finalYrpercent)
                 AND (@currentDegreePercentage is null current_degree_percent>=@currentDegreePercentage)
                 AND (@highSchoolPercentage is null high_school_percentage>=@highSchoolPercentage)
                 AND (@higherSchoolPercentage is null higher_school_percentage>=@higherSchoolPercentage)
                 AND (@graduationPercent is null graduation_percent>=@graduationPercentage)
                 AND (@diplomaPercentage is null diploma_percentage>=@diplomaPercenage)
                 AND (@noOfAtkt is null or no_of_atkt<=@noOfAtkt)
                 AND (@date is null or date_of_birth>=@date)";

First, if branchId is a string, then you'll need these single quotes:

branch_id IN('"+branchId+"') AND 

though I don't understand why it's not parameterized like so:

branch_id = @branchId AND 

Second, you may have misspelled the word 'year' in this field name:

AND  (@firstYrPercent is null or first_year_percent>=@firstYrPercent

Finally, you're missing a few OR's here:

AND  (@currentDegreePercentage is null OR current_degree_percent>=@currentDegreePercentage)
AND  (@highSchoolPercentage is null OR high_school_percentage>=@highSchoolPercentage)
AND  (@higherSchoolPercentage is null OR higher_school_percentage>=@higherSchoolPercentage)
AND  (@graduationPercent is null OR graduation_percent>=@graduationPercentage)
AND  (@diplomaPercentage is null OR diploma_percentage>=@diplomaPercenage)

I think I got it.

Are you getting an error while trying to COMPILE the code, as opposed to running the SQL query?

I'm going to bet that you're using C#, and that you should do multi-line strings with an @-symbol before the "-symbol. Such as this:

string blabla = @"
     hello
     there
";

Then of course you need it also when you open up the string after branchId