Add hybrid float formatting: use 'f' format with fallback to 'g' for extreme values

Co-authored-by: dlevy-msft-sql <[email protected]>

Author: Copilot

pkg/sqlcmd/format.go

@@ -533,12 +533,26 @@ func (f *sqlCmdFormatterType) scanRow(rows *sql.Rows) ([]string, error) {
 				}
 			case float64:
 				// Format float64 to match ODBC sqlcmd behavior
-				// Use 'f' format with -1 precision to avoid scientific notation
-				// and to show all significant digits
-				row[n] = strconv.FormatFloat(x, 'f', -1, 64)
+				// Use 'f' format with -1 precision to avoid scientific notation for typical values
+				// Fall back to 'g' format if the result would exceed the column display width
+				formatted := strconv.FormatFloat(x, 'f', -1, 64)
+				displayWidth := f.columnDetails[n].displayWidth
+				if displayWidth > 0 && int64(len(formatted)) > displayWidth {
+					// Use 'g' format for very large/small values to avoid truncation issues
+					formatted = strconv.FormatFloat(x, 'g', -1, 64)
+				}
+				row[n] = formatted
 			case float32:
 				// Format float32 to match ODBC sqlcmd behavior
-				row[n] = strconv.FormatFloat(float64(x), 'f', -1, 32)
+				// Use 'f' format with -1 precision to avoid scientific notation for typical values
+				// Fall back to 'g' format if the result would exceed the column display width
+				formatted := strconv.FormatFloat(float64(x), 'f', -1, 32)
+				displayWidth := f.columnDetails[n].displayWidth
+				if displayWidth > 0 && int64(len(formatted)) > displayWidth {
+					// Use 'g' format for very large/small values to avoid truncation issues
+					formatted = strconv.FormatFloat(float64(x), 'g', -1, 32)
+				}
+				row[n] = formatted
 			default:
 				var err error
 				if row[n], err = fmt.Sprintf("%v", x), nil; err != nil {

pkg/sqlcmd/format_test.go

@@ -194,3 +194,24 @@ func TestFormatterFloatFormatting(t *testing.T) {
 	assert.Contains(t, output, "788569.3655858", "Output should contain decimal representation of Longitude3")
 	assert.Contains(t, output, "4714608.041809", "Output should contain decimal representation of Latitude3")
 }
+
+func TestFormatterFloatFormattingExtremeValues(t *testing.T) {
+	// Test that extreme float values fall back to scientific notation
+	// to avoid truncation issues with very large or very small numbers
+	s, buf := setupSqlCmdWithMemoryOutput(t)
+	defer buf.Close()
+
+	// Test query with extreme float values that would exceed the 24-char display width
+	query := `SELECT 
+		CAST(1e100 AS FLOAT) as VeryLarge,
+		CAST(1e-100 AS FLOAT) as VerySmall`
+
+	err := runSqlCmd(t, s, []string{query, "GO"})
+	assert.NoError(t, err, "runSqlCmd returned error")
+
+	output := buf.buf.String()
+
+	// Verify that extremely large/small values use scientific notation
+	// (because decimal format would exceed the 24-char column width)
+	assert.Contains(t, output, "e+", "Output should contain scientific notation for extreme values")
+}