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dolthub/dolt#7128 - String to number conversion #3136

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9a292fc
impl with configurable string to number
elianddb Aug 4, 2025
376e53c
[ga-format-pr] Run ./format_repo.sh to fix formatting
elianddb Aug 4, 2025
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147 changes: 147 additions & 0 deletions enginetest/queries/variable_queries.go
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Original file line number Diff line number Diff line change
Expand Up @@ -633,6 +633,153 @@ var VariableQueries = []ScriptTest{
},
},
},
{
Name: "mysql_string_to_number system variable",
Assertions: []ScriptTestAssertion{
{
Query: "SELECT @@mysql_string_to_number",
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Are these copied from another test? Do these different variables interact with each other?

I'm worried this is copy-pasting code and tests. If we have a lot of variables that all have global/session/local variables like this with specific rules, we should probably have a special test for those that doesn't duplicate code.

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)}},
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The original behavior throws an error, right? This test seems to imply that it returns 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",
Expand Down
15 changes: 14 additions & 1 deletion sql/expression/convert.go
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Original file line number Diff line number Diff line change
Expand Up @@ -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 {
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So if the flag is set, we convert to a decimal by converting to a float first?

It's not clear from looking at this function why this produces the correct behavior.

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
Expand Down
13 changes: 13 additions & 0 deletions sql/sql_mode.go
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Expand Up @@ -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
}
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