Question

I’m working on code that will scan a db table for column names, and then build a SQL statement to create table based upon a subset of columns. The end statement can be quite huge (60 cols in some instances).

Here’s a small snippet:

        case ["VARCHAR", "CHAR"]:
            clause = "${row.name} ${row.colType.trim()}(${row.length})"
            break 

My question is when I should force interpolation of the GString. Currently I wait until I build the entire statement, then call .toString() at the very end. Would it make any difference if I called .toString() at this level instead?

More code:

            //CONTEXT
    def rs = inputs.connection.sqlConnection.eachRow(tableNamesSql){ row ->
                clause = buildSqlClause(row)
                columnNames.append(clause).append(',\n') 
    }
    def formatted = columnNames.toString().replaceAll(",\$", "")

    def sql = """CREATE TABLE ${inputs.outputSchemaName}.${inputs.outputTableName}_${inputs.cycle} (
            ${formatted}
            ) IN TBTS_${inputs.outputSchemaName}""" 

And the code that analyzes the row:

def buildSqlClause(row){
        def clause

        switch(row.colType.trim()){
            case "INTEGER":
                clause = "${row.name} ${row.colType.trim()}"
                break
            case "DECIMAL":
                clause = "${row.name} ${row.colType.trim()}(${row.length}, ${row.scale})"
                break
            case ["VARCHAR", "CHAR"]:
                clause = "${row.name} ${row.colType.trim()}(${row.length})"
                break
            case "TIMESTMP":
                clause = "${row.name} TIMESTAMP"
                break
            case "DATE":
                clause = "${row.name} ${row.colType.trim()}"
                break
            default: throw new Exception("Invalid SQL data type: [${row.colType}]")
        }
        def nullVal = row.nulls
        if(nullVal.equalsIgnoreCase("N")){
            clause = "${clause} NOT NULL"
        }
        return clause


}

So in other words, in the case of a db column “foo” I need the sql clause to read
FOO VARCHAR(INT).

Answer 1

Do you need to call toString() at all?

Also, you might get better results collecting a List of field definition string (as you are doing), then call join to stitch them all together?