dynamic

MySQL pivot table query with dynamic columns

The only way in MySQL to do this dynamically is with Prepared statements. Here is a good article about them: Dynamic pivot tables (transform rows to columns) Your code would look like this: SET @sql = NULL; SELECT GROUP_CONCAT(DISTINCT CONCAT( ‘MAX(IF(pa.fieldname=””‘, fieldname, ”’, pa.fieldvalue, NULL)) AS ‘, fieldname ) ) INTO @sql FROM product_additional; SET … Read more

What is the difference between call and apply?

The difference is that apply lets you invoke the function with arguments as an array; call requires the parameters be listed explicitly. A useful mnemonic is “A for array and C for comma.” See MDN’s documentation on apply and call. Pseudo syntax: theFunction.apply(valueForThis, arrayOfArgs) theFunction.call(valueForThis, arg1, arg2, …) There is also, as of ES6, the … Read more

System.Linq.Expression.Compile error

Resolved. The method was called recursively, creating the parameter and the expression and returned to himself. In this process the parameters were removed from memory, as they had already been used believed not to have problems. But they need to be kept in memory until the time of compilation. In this case I used a … Read more