null-handling

MySQL : How to get records are have non null values ?

I want to get all records in case the result_1 is not null like below : SELECT ID, Code, NULLIF(CompareWithField,2.25) as result_1 FROM `data` WHERE Indexed = 0 and code = 142 and 'result_1' is not null But instead, every time I run the query, I receive a result even if result_1 reports NULL. Any solution ?...

C# Handling Null Values

I have CustomerID declared as int? CustomerID=null; I am checking null values while reading DataReader Id = reader["CustomerId"] is DBNull ? null :Convert.ToInt32(reader["CustomerID"]); It is throwing Type of conditional expression cannot be determined because there is no implicit conversion between '<null>' and 'int' W...

SQL query LEFT JOIN issue (MySQL)

I have 2 tables SCHOOLS (ID, SCHOOL_NAME, CITY_ID) STUDENTS (ID, STUDENT_NAME, SCHOOL_ID). I want to list schools in a particular city along with the student count (School Name| Student Count) One way to do this is to have co-related subquery - select sh.school_name, (select count(*) from student where s...