In c# code it is possible to call SQL commands using the SqlCommand object like below:
string selectString = @”select MyColumn from Mytable where MyOtherColumn = ” + value;
SqlCommand cmd = new SqlCommand();
cmd.CommandText = selectString;
cmd.Connection = conn;
The code above should be using parameterized statements or stored procedures. A parameterized statement is shown below.
string selectString = @”select MyColumn from Mytable where MyOtherColumn = @value1″; -see SQL Injection: Use Parameterisation
Using a parameterized statements will double quote\escape the input and prevent any issues or catenation of statements.
To code review search in your code for SqlCommand string and then check each one is using ideally a stored procedure or at worst a parameterised SQL statement. If the statement string is appended together from other strings look carefully at the source and consider whitelisting. Never append a string a user has supplied either in a form or stored from previous input in your db, instead use a parameterized statement or a stored procedure.