impl with configurable string to number

Author: elianddb

enginetest/queries/variable_queries.go

@@ -633,6 +633,153 @@ var VariableQueries = []ScriptTest{
 			},
 		},
 	},
+	{
+		Name: "mysql_string_to_number system variable",
+		Assertions: []ScriptTestAssertion{
+			{
+				Query:    "SELECT @@mysql_string_to_number",
+				Expected: []sql.Row{{int8(0)}},
+			},
+			{
+				Query:    "SET @@mysql_string_to_number = 1",
+				Expected: []sql.Row{{types.NewOkResult(0)}},
+			},
+			{
+				Query:    "SELECT @@mysql_string_to_number",
+				Expected: []sql.Row{{int8(1)}},
+			},
+			{
+				Query:    "SET @@mysql_string_to_number = 0",
+				Expected: []sql.Row{{types.NewOkResult(0)}},
+			},
+			{
+				Query:    "SELECT @@mysql_string_to_number",
+				Expected: []sql.Row{{int8(0)}},
+			},
+			{
+				Query:    "SET @@session.mysql_string_to_number = 1",
+				Expected: []sql.Row{{types.NewOkResult(0)}},
+			},
+			{
+				Query:    "SELECT @@session.mysql_string_to_number",
+				Expected: []sql.Row{{int8(1)}},
+			},
+			{
+				Query:    "SET @@global.mysql_string_to_number = 0",
+				Expected: []sql.Row{{types.NewOkResult(0)}},
+			},
+			{
+				Query:    "SELECT @@global.mysql_string_to_number",
+				Expected: []sql.Row{{int8(0)}},
+			},
+		},
+	},
+	{
+		Name: "mysql_string_to_number conversion behavior",
+		SetUpScript: []string{
+			"CREATE TABLE test_table (id INT PRIMARY KEY, int_col INT, float_col FLOAT)",
+			"INSERT INTO test_table VALUES (1, 10, 10.5)",
+		},
+		Assertions: []ScriptTestAssertion{
+			// Variable disabled - original behavior
+			{
+				Query:    "SET @@mysql_string_to_number = 0",
+				Expected: []sql.Row{{types.NewOkResult(0)}},
+			},
+			{
+				Query:    "SELECT CAST('123abc' AS SIGNED)",
+				Expected: []sql.Row{{int64(0)}},
+			},
+			{
+				Query:    "SELECT CAST('_123_' AS SIGNED)",
+				Expected: []sql.Row{{int64(0)}},
+			},
+			{
+				Query:    "SELECT CAST('abc123' AS SIGNED)",
+				Expected: []sql.Row{{int64(0)}},
+			},
+			// Variable enabled - extract numeric prefixes
+			{
+				Query:    "SET @@mysql_string_to_number = 1",
+				Expected: []sql.Row{{types.NewOkResult(0)}},
+			},
+			{
+				Query:    "SELECT CAST('123abc' AS SIGNED)",
+				Expected: []sql.Row{{int64(123)}},
+			},
+			{
+				Query:    "SELECT CAST('_123_' AS SIGNED)",
+				Expected: []sql.Row{{int64(0)}},
+			},
+			{
+				Query:    "SELECT CAST('123_' AS SIGNED)",
+				Expected: []sql.Row{{int64(123)}},
+			},
+			{
+				Query:    "SELECT CAST('abc123' AS SIGNED)",
+				Expected: []sql.Row{{int64(0)}},
+			},
+			{
+				Query:    "SELECT CAST(' 123 ' AS SIGNED)",
+				Expected: []sql.Row{{int64(123)}},
+			},
+			{
+				Query:    "SELECT CAST('  +45.67e2' AS SIGNED)",
+				Expected: []sql.Row{{int64(45)}},
+			},
+			{
+				Query:    "SELECT CAST('-789.123' AS SIGNED)",
+				Expected: []sql.Row{{int64(-789)}},
+			},
+			{
+				Query:    "SELECT CAST('123%' AS SIGNED)",
+				Expected: []sql.Row{{int64(123)}},
+			},
+			{
+				Query:    "SELECT CAST('#123' AS SIGNED)",
+				Expected: []sql.Row{{int64(0)}},
+			},
+			{
+				Query:    "SELECT CAST('123.456' AS SIGNED)",
+				Expected: []sql.Row{{int64(123)}},
+			},
+			// Test decimal conversions
+			{
+				Query:    "SELECT CAST('123.456abc' AS DECIMAL(10,3))",
+				Expected: []sql.Row{{"123.456"}},
+			},
+			{
+				Query:    "SELECT CAST('_123.456_' AS DECIMAL(10,3))",
+				Expected: []sql.Row{{"0.000"}},
+			},
+			{
+				Query:    "SELECT CAST('45.67e2' AS DECIMAL(10,2))",
+				Expected: []sql.Row{{"4567.00"}},
+			},
+			// Test unsigned type handling
+			{
+				Query:    "SELECT CAST('123abc' AS UNSIGNED)",
+				Expected: []sql.Row{{uint64(123)}},
+			},
+			{
+				Query:    "SELECT CAST('-123abc' AS UNSIGNED)",
+				Expected: []sql.Row{{uint64(18446744073709551493)}},
+			},
+			// Test comparison operations from issue #7128
+			{
+				Query:    "SELECT * FROM test_table WHERE int_col = '10abc'",
+				Expected: []sql.Row{{1, 10, float32(10.5)}},
+			},
+			{
+				Query:    "SELECT * FROM test_table WHERE float_col = '10.5xyz'",
+				Expected: []sql.Row{{1, 10, float32(10.5)}},
+			},
+			{
+				Query:    "SELECT * FROM test_table WHERE int_col = '_10_'",
+				Expected: []sql.Row{},
+			},
+		},
+	},
 	//TODO: do not override tables with user-var-like names...but why would you do this??
 	//{
 	//	Name: "user var table name no conflict",

sql/expression/convert.go

@@ -339,11 +339,24 @@ func convertValue(ctx *sql.Context, val interface{}, castTo string, originType s
 		}
 		return d, nil
 	case ConvertToDecimal:
+		dt := createConvertedDecimalType(typeLength, typeScale, false)
+		
+		// Handle string-to-decimal conversion for mysql_string_to_number mode
+		if strVal, ok := val.(string); ok && sql.ValidateStringToNumberMode(ctx) {
+			if convertedVal, _, err := types.Float64.Convert(ctx, strVal); err == nil {
+				d, _, err := dt.Convert(ctx, convertedVal)
+				if err != nil {
+					return dt.Zero(), nil
+				}
+				return d, nil
+			}
+		}
+		
 		value, err := convertHexBlobToDecimalForNumericContext(val, originType)
 		if err != nil {
 			return nil, err
 		}
-		dt := createConvertedDecimalType(typeLength, typeScale, false)
+		
 		d, _, err := dt.Convert(ctx, value)
 		if err != nil {
 			return dt.Zero(), nil

sql/sql_mode.go

@@ -128,3 +128,16 @@ func ValidateStrictMode(ctx *Context) bool {
 	sqlMode := LoadSqlMode(ctx)
 	return sqlMode.ModeEnabled("STRICT_TRANS_TABLES") || sqlMode.ModeEnabled("STRICT_ALL_TABLES")
 }
+
+// ValidateStringToNumberMode returns true if mysql_string_to_number is enabled
+func ValidateStringToNumberMode(ctx *Context) bool {
+	if ctx == nil {
+		return false
+	}
+	if val, err := ctx.GetSessionVariable(ctx, "mysql_string_to_number"); err == nil {
+		if mysqlCompat, ok := val.(int8); ok {
+			return mysqlCompat != 0
+		}
+	}
+	return false
+}