Revert "Add string type to ColumnTypeScanType(). (go-sql-driver#976)" (go-sql-driver#1018)

This reverts commit 5ee934f.

Author: julienschmidt

AUTHORS

@@ -45,7 +45,6 @@ Jeff Hodges <jeff at somethingsimilar.com>
 Jeffrey Charles <jeffreycharles at gmail.com>
 Jerome Meyer <jxmeyer at gmail.com>
 Jian Zhen <zhenjl at gmail.com>
-Johann Forster <johannforster15 at gmail.com>
 Joshua Prunier <joshua.prunier at gmail.com>
 Julien Lefevre <julien.lefevr at gmail.com>
 Julien Schmidt <go-sql-driver at julienschmidt.com>

driver_test.go

@@ -2733,9 +2733,6 @@ func TestRowsColumnTypes(t *testing.T) {
 	rb0pad4 := sql.RawBytes("0\x00\x00\x00") // BINARY right-pads values with 0x00
 	rbx0 := sql.RawBytes("\x00")
 	rbx42 := sql.RawBytes("\x42")
-	s0 := sql.NullString{String: "0", Valid: true}
-	sNULL := sql.NullString{String: "", Valid: false}
-	sTest := sql.NullString{String: "Test", Valid: true}
 
 	var columns = []struct {
 		name             string
@@ -2774,18 +2771,18 @@ func TestRowsColumnTypes(t *testing.T) {
 		{"decimal2null", "DECIMAL(8,4)", "DECIMAL", scanTypeRawBytes, true, 8, 4, [3]string{"0", "NULL", "1234.123456"}, [3]interface{}{sql.RawBytes("0.0000"), rbNULL, sql.RawBytes("1234.1235")}},
 		{"decimal3", "DECIMAL(5,0) NOT NULL", "DECIMAL", scanTypeRawBytes, false, 5, 0, [3]string{"0", "13.37", "-12345.123456"}, [3]interface{}{rb0, sql.RawBytes("13"), sql.RawBytes("-12345")}},
 		{"decimal3null", "DECIMAL(5,0)", "DECIMAL", scanTypeRawBytes, true, 5, 0, [3]string{"0", "NULL", "-12345.123456"}, [3]interface{}{rb0, rbNULL, sql.RawBytes("-12345")}},
-		{"char25null", "CHAR(25)", "CHAR", scanTypeNullString, true, 0, 0, [3]string{"0", "NULL", "'Test'"}, [3]interface{}{s0, sNULL, sTest}},
-		{"varchar42", "VARCHAR(42) NOT NULL", "VARCHAR", scanTypeString, false, 0, 0, [3]string{"0", "'Test'", "42"}, [3]interface{}{"0", "Test", "42"}},
+		{"char25null", "CHAR(25)", "CHAR", scanTypeRawBytes, true, 0, 0, [3]string{"0", "NULL", "'Test'"}, [3]interface{}{rb0, rbNULL, rbTest}},
+		{"varchar42", "VARCHAR(42) NOT NULL", "VARCHAR", scanTypeRawBytes, false, 0, 0, [3]string{"0", "'Test'", "42"}, [3]interface{}{rb0, rbTest, rb42}},
 		{"binary4null", "BINARY(4)", "BINARY", scanTypeRawBytes, true, 0, 0, [3]string{"0", "NULL", "'Test'"}, [3]interface{}{rb0pad4, rbNULL, rbTest}},
 		{"varbinary42", "VARBINARY(42) NOT NULL", "VARBINARY", scanTypeRawBytes, false, 0, 0, [3]string{"0", "'Test'", "42"}, [3]interface{}{rb0, rbTest, rb42}},
 		{"tinyblobnull", "TINYBLOB", "BLOB", scanTypeRawBytes, true, 0, 0, [3]string{"0", "NULL", "'Test'"}, [3]interface{}{rb0, rbNULL, rbTest}},
-		{"tinytextnull", "TINYTEXT", "TEXT", scanTypeNullString, true, 0, 0, [3]string{"0", "NULL", "'Test'"}, [3]interface{}{s0, sNULL, sTest}},
+		{"tinytextnull", "TINYTEXT", "TEXT", scanTypeRawBytes, true, 0, 0, [3]string{"0", "NULL", "'Test'"}, [3]interface{}{rb0, rbNULL, rbTest}},
 		{"blobnull", "BLOB", "BLOB", scanTypeRawBytes, true, 0, 0, [3]string{"0", "NULL", "'Test'"}, [3]interface{}{rb0, rbNULL, rbTest}},
-		{"textnull", "TEXT", "TEXT", scanTypeNullString, true, 0, 0, [3]string{"0", "NULL", "'Test'"}, [3]interface{}{s0, sNULL, sTest}},
+		{"textnull", "TEXT", "TEXT", scanTypeRawBytes, true, 0, 0, [3]string{"0", "NULL", "'Test'"}, [3]interface{}{rb0, rbNULL, rbTest}},
 		{"mediumblob", "MEDIUMBLOB NOT NULL", "BLOB", scanTypeRawBytes, false, 0, 0, [3]string{"0", "'Test'", "42"}, [3]interface{}{rb0, rbTest, rb42}},
-		{"mediumtext", "MEDIUMTEXT NOT NULL", "TEXT", scanTypeString, false, 0, 0, [3]string{"0", "'Test'", "42"}, [3]interface{}{"0", "Test", "42"}},
+		{"mediumtext", "MEDIUMTEXT NOT NULL", "TEXT", scanTypeRawBytes, false, 0, 0, [3]string{"0", "'Test'", "42"}, [3]interface{}{rb0, rbTest, rb42}},
 		{"longblob", "LONGBLOB NOT NULL", "BLOB", scanTypeRawBytes, false, 0, 0, [3]string{"0", "'Test'", "42"}, [3]interface{}{rb0, rbTest, rb42}},
-		{"longtext", "LONGTEXT NOT NULL", "TEXT", scanTypeString, false, 0, 0, [3]string{"0", "'Test'", "42"}, [3]interface{}{"0", "Test", "42"}},
+		{"longtext", "LONGTEXT NOT NULL", "TEXT", scanTypeRawBytes, false, 0, 0, [3]string{"0", "'Test'", "42"}, [3]interface{}{rb0, rbTest, rb42}},
 		{"datetime", "DATETIME", "DATETIME", scanTypeNullTime, true, 0, 0, [3]string{"'2006-01-02 15:04:05'", "'2006-01-02 15:04:05.1'", "'2006-01-02 15:04:05.111111'"}, [3]interface{}{nt0, nt0, nt0}},
 		{"datetime2", "DATETIME(2)", "DATETIME", scanTypeNullTime, true, 2, 2, [3]string{"'2006-01-02 15:04:05'", "'2006-01-02 15:04:05.1'", "'2006-01-02 15:04:05.111111'"}, [3]interface{}{nt0, nt1, nt2}},
 		{"datetime6", "DATETIME(6)", "DATETIME", scanTypeNullTime, true, 6, 6, [3]string{"'2006-01-02 15:04:05'", "'2006-01-02 15:04:05.1'", "'2006-01-02 15:04:05.111111'"}, [3]interface{}{nt0, nt1, nt6}},

fields.go

@@ -98,23 +98,21 @@ func (mf *mysqlField) typeDatabaseName() string {
 }
 
 var (
-	scanTypeFloat32    = reflect.TypeOf(float32(0))
-	scanTypeFloat64    = reflect.TypeOf(float64(0))
-	scanTypeInt8       = reflect.TypeOf(int8(0))
-	scanTypeInt16      = reflect.TypeOf(int16(0))
-	scanTypeInt32      = reflect.TypeOf(int32(0))
-	scanTypeInt64      = reflect.TypeOf(int64(0))
-	scanTypeNullFloat  = reflect.TypeOf(sql.NullFloat64{})
-	scanTypeNullInt    = reflect.TypeOf(sql.NullInt64{})
-	scanTypeNullTime   = reflect.TypeOf(NullTime{})
-	scanTypeUint8      = reflect.TypeOf(uint8(0))
-	scanTypeUint16     = reflect.TypeOf(uint16(0))
-	scanTypeUint32     = reflect.TypeOf(uint32(0))
-	scanTypeUint64     = reflect.TypeOf(uint64(0))
-	scanTypeString     = reflect.TypeOf(string(""))
-	scanTypeNullString = reflect.TypeOf(sql.NullString{})
-	scanTypeRawBytes   = reflect.TypeOf(sql.RawBytes{})
-	scanTypeUnknown    = reflect.TypeOf(new(interface{}))
+	scanTypeFloat32   = reflect.TypeOf(float32(0))
+	scanTypeFloat64   = reflect.TypeOf(float64(0))
+	scanTypeInt8      = reflect.TypeOf(int8(0))
+	scanTypeInt16     = reflect.TypeOf(int16(0))
+	scanTypeInt32     = reflect.TypeOf(int32(0))
+	scanTypeInt64     = reflect.TypeOf(int64(0))
+	scanTypeNullFloat = reflect.TypeOf(sql.NullFloat64{})
+	scanTypeNullInt   = reflect.TypeOf(sql.NullInt64{})
+	scanTypeNullTime  = reflect.TypeOf(NullTime{})
+	scanTypeUint8     = reflect.TypeOf(uint8(0))
+	scanTypeUint16    = reflect.TypeOf(uint16(0))
+	scanTypeUint32    = reflect.TypeOf(uint32(0))
+	scanTypeUint64    = reflect.TypeOf(uint64(0))
+	scanTypeRawBytes  = reflect.TypeOf(sql.RawBytes{})
+	scanTypeUnknown   = reflect.TypeOf(new(interface{}))
 )
 
 type mysqlField struct {
@@ -177,21 +175,11 @@ func (mf *mysqlField) scanType() reflect.Type {
 		}
 		return scanTypeNullFloat
 
-	case fieldTypeVarChar, fieldTypeString, fieldTypeVarString, fieldTypeTinyBLOB,
-		fieldTypeMediumBLOB, fieldTypeLongBLOB, fieldTypeBLOB:
-		// charsetnr == 63 means this column is binary.
-		// https://dev.mysql.com/doc/refman/8.0/en/c-api-data-structures.html
-		if mf.charSet == 63 {
-			return scanTypeRawBytes
-		}
-		if mf.flags&flagNotNULL != 0 {
-			return scanTypeString
-		}
-		return scanTypeNullString
-
-	case fieldTypeDecimal, fieldTypeNewDecimal, fieldTypeBit,
-		fieldTypeEnum, fieldTypeSet,
-		fieldTypeGeometry, fieldTypeJSON, fieldTypeTime:
+	case fieldTypeDecimal, fieldTypeNewDecimal, fieldTypeVarChar,
+		fieldTypeBit, fieldTypeEnum, fieldTypeSet, fieldTypeTinyBLOB,
+		fieldTypeMediumBLOB, fieldTypeLongBLOB, fieldTypeBLOB,
+		fieldTypeVarString, fieldTypeString, fieldTypeGeometry, fieldTypeJSON,
+		fieldTypeTime:
 		return scanTypeRawBytes
 
 	case fieldTypeDate, fieldTypeNewDate,