please correct me with the sql query - sql

Question

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]
WHERE 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)";

Answer 1

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)

Answer 2

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