sql: change the parameter ExtractSQLFields to driver name

Previously, we use the string as parameter to set the returned place
holders.

This commit changes the parameter to the driver name so if the value
is "postgres" the place holders will be returned as counter, for example
"$1", "$2", and so on.

2 files changed, 31 insertions, 15 deletions

diff --git a/lib/sql/row.go b/lib/sql/row.go
index 13b43978..2e0eb374 100644
--- a/lib/sql/row.go
+++ b/lib/sql/row.go
@@ -4,7 +4,10 @@
 
 package sql
 
-import "sort"
+import (
+	"fmt"
+	"sort"
+)
 
 //
 // Row represent a column-name and value in a tuple.
@@ -15,18 +18,21 @@ import "sort"
 type Row map[string]interface{}
 
 //
-// ExtractSQLFields extract the column's name, column place holder (default is
-// "?"), and column values; as slices.
+// ExtractSQLFields extract the column's name, column place holder, and column
+// values as slices.
+//
+// The driverName define the returned place holders.
+// If the driverName is "postgres" then the list of holders will be returned
+// as counter, for example "$1", "$2" and so on.
+// If the driverName is "mysql" or empty or unknown the the list of holders
+// will be returned as list of "?".
 //
 // The returned names will be sorted in ascending order.
 //
-func (row Row) ExtractSQLFields(placeHolder string) (names, holders []string, values []interface{}) {
+func (row Row) ExtractSQLFields(driverName string) (names, holders []string, values []interface{}) {
 	if len(row) == 0 {
 		return nil, nil, nil
 	}
-	if len(placeHolder) == 0 {
-		placeHolder = DefaultPlaceHolder
-	}
 
 	names = make([]string, 0, len(row))
 	holders = make([]string, 0, len(row))
@@ -37,8 +43,12 @@ func (row Row) ExtractSQLFields(placeHolder string) (names, holders []string, va
 	}
 	sort.Strings(names)
 
-	for _, k := range names {
-		holders = append(holders, placeHolder)
+	for x, k := range names {
+		if driverName == DriverNamePostgres {
+			holders = append(holders, fmt.Sprintf("$%d", x+1))
+		} else {
+			holders = append(holders, DefaultPlaceHolder)
+		}
 		values = append(values, row[k])
 	}
 
diff --git a/lib/sql/row_example_test.go b/lib/sql/row_example_test.go
index d7cd0918..e22524a4 100644
--- a/lib/sql/row_example_test.go
+++ b/lib/sql/row_example_test.go
@@ -11,17 +11,23 @@ func ExampleRow_ExtractSQLFields() {
 		"col_2": 1,
 		"col_1": true,
 	}
-	names, holders, values := row.ExtractSQLFields(DefaultPlaceHolder)
+	names, holders, values := row.ExtractSQLFields("?")
 	fnames := strings.Join(names, ",")
 	fholders := strings.Join(holders, ",")
-
 	q := `INSERT INTO table (` + fnames + `) VALUES (` + fholders + `)`
-	fmt.Println(q)
+	fmt.Printf("Query: %s\n", q)
+
+	names, holders, values = row.ExtractSQLFields("postgres")
+	fnames = strings.Join(names, ",")
+	fholders = strings.Join(holders, ",")
+	q = `INSERT INTO table (` + fnames + `) VALUES (` + fholders + `)`
+	fmt.Printf("Query for PostgreSQL: %s\n", q)
 
 	// err := db.Exec(q, values...)
 	fmt.Println(values)
 
-	//Output:
-	//INSERT INTO table (col_1,col_2,col_3) VALUES (?,?,?)
-	//[true 1 'update']
+	// Output:
+	// Query: INSERT INTO table (col_1,col_2,col_3) VALUES (?,?,?)
+	// Query for PostgreSQL: INSERT INTO table (col_1,col_2,col_3) VALUES ($1,$2,$3)
+	// [true 1 'update']
 }