Add StringColumn type and expression

Add Projection type
Alias refactoring
More numeric operations

generator/metadata/column_info.go

@@ -26,6 +26,31 @@ func (c ColumnInfo) ToGoVarName() string {
 	return snaker.SnakeToCamel(c.Name) + "Column"
 }
 
+func (c ColumnInfo) ToSqlBuilderColumnType() string {
+	switch c.DataType {
+	case "boolean":
+		return "BoolColumn"
+	case "smallint":
+		return "IntegerColumn"
+	case "integer":
+		return "IntegerColumn"
+	case "bigint":
+		return "IntegerColumn"
+	case "date", "timestamp without time zone", "timestamp with time zone":
+		return "StringColumn"
+	case "bytea":
+		return "StringColumn"
+	case "text":
+		return "StringColumn"
+	case "real":
+		return "NumericColumn"
+	case "numeric", "double precision":
+		return "NumericColumn"
+	default:
+		return "StringColumn"
+	}
+}
+
 func (c ColumnInfo) ToGoType() string {
 	typeStr := c.GoBaseType()
 	if c.IsNullable || c.TableInfo.IsForeignKey(c.Name) {