More work on sql schema and migrations, starting to get somewhere

pkg/services/sqlstore/migrations/dialect.go

@@ -0,0 +1,52 @@
+package migrations
+
+import "fmt"
+
+type Dialect interface {
+	DriverName() string
+	ToDBTypeSql(columnType ColumnType, length int) string
+	TableCheckSql(tableName string) (string, []interface{})
+}
+
+type Sqlite3 struct {
+}
+
+type Mysql struct {
+}
+
+func (db *Sqlite3) DriverName() string {
+	return SQLITE
+}
+
+func (db *Mysql) DriverName() string {
+	return MYSQL
+}
+
+func (db *Sqlite3) ToDBTypeSql(columnType ColumnType, length int) string {
+	switch columnType {
+	case DB_TYPE_STRING:
+		return "TEXT"
+	}
+
+	panic("Unsupported db type")
+}
+
+func (db *Mysql) ToDBTypeSql(columnType ColumnType, length int) string {
+	switch columnType {
+	case DB_TYPE_STRING:
+		return fmt.Sprintf("NVARCHAR(%d)", length)
+	}
+
+	panic("Unsupported db type")
+}
+
+func (db *Sqlite3) TableCheckSql(tableName string) (string, []interface{}) {
+	args := []interface{}{tableName}
+	return "SELECT name FROM sqlite_master WHERE type='table' and name = ?", args
+}
+
+func (db *Mysql) TableCheckSql(tableName string) (string, []interface{}) {
+	args := []interface{}{"grafana", tableName}
+	sql := "SELECT `TABLE_NAME` from `INFORMATION_SCHEMA`.`TABLES` WHERE `TABLE_SCHEMA`=? and `TABLE_NAME`=?"
+	return sql, args
+}