Export sqlite3_column_table_name (#900)

sqlite3.go

@@ -19,6 +19,7 @@ package sqlite3
 #cgo CFLAGS: -DSQLITE_OMIT_DEPRECATED
 #cgo CFLAGS: -DSQLITE_DEFAULT_WAL_SYNCHRONOUS=1
 #cgo CFLAGS: -DSQLITE_ENABLE_UPDATE_DELETE_LIMIT
+#cgo CFLAGS: -DSQLITE_ENABLE_COLUMN_METADATA
 #cgo CFLAGS: -Wno-deprecated-declarations
 #cgo linux,!android CFLAGS: -DHAVE_PREAD64=1 -DHAVE_PWRITE64=1
 #ifndef USE_LIBSQLITE3
@@ -2014,6 +2015,14 @@ func (s *SQLiteStmt) Readonly() bool {
 	return C.sqlite3_stmt_readonly(s.s) == 1
 }
 
+// ColumnTableName returns the table that is the origin of a particular result
+// column in a SELECT statement.
+//
+// See https://www.sqlite.org/c3ref/column_database_name.html
+func (s *SQLiteStmt) ColumnTableName(n int) string {
+        return C.GoString(C.sqlite3_column_table_name(s.s, C.int(n)))
+}
+
 // Close the rows.
 func (rc *SQLiteRows) Close() error {
 	rc.s.mu.Lock()

sqlite3_test.go

@@ -1604,6 +1604,40 @@ func TestDeclTypes(t *testing.T) {
 	}
 }
 
+func TestColumnTableName(t *testing.T) {
+        d := SQLiteDriver{}
+        conn, err := d.Open(":memory:")
+        if err != nil {
+                t.Fatal("failed to get database connection:", err)
+        }
+        defer conn.Close()
+        sqlite3conn := conn.(*SQLiteConn)
+
+        _, err = sqlite3conn.Exec(`CREATE TABLE foo (name string)`, nil)
+        if err != nil {
+                t.Fatal("Failed to create table:", err)
+        }
+        _, err = sqlite3conn.Exec(`CREATE TABLE bar (name string)`, nil)
+        if err != nil {
+                t.Fatal("Failed to create table:", err)
+        }
+
+        stmt, err := sqlite3conn.Prepare(`SELECT * FROM foo JOIN bar ON foo.name = bar.name`)
+        if err != nil {
+                t.Fatal(err)
+        }
+
+        if exp, got := "foo", stmt.(*SQLiteStmt).ColumnTableName(0); exp != got {
+                t.Fatalf("Incorrect table name returned expected: %s, got: %s", exp, got)
+        }
+        if exp, got := "bar", stmt.(*SQLiteStmt).ColumnTableName(1); exp != got {
+                t.Fatalf("Incorrect table name returned expected: %s, got: %s", exp, got)
+        }
+        if exp, got := "", stmt.(*SQLiteStmt).ColumnTableName(2); exp != got {
+                t.Fatalf("Incorrect table name returned expected: %s, got: %s", exp, got)
+        }
+}
+
 func TestPinger(t *testing.T) {
 	db, err := sql.Open("sqlite3", ":memory:")
 	if err != nil {