如何在SWIFT中的sqlite表中添加列

Question

我尝试用swift在表中添加一列.

我的代码:

  connect_db();
  adddbfield("mynewfield","mytable");

.

func connect_db() -> Bool {
    let sDBPath=<is correctly set>;
    if sqlite3_open(sDBPath, &db) != SQLITE_OK {
        println("Failed to open db")
        return false;
    }else{
        return true;
    }
}

.

func adddbfield(sFieldName:String, sTable:String) -> Bool {
    var bReturn:Bool=false;
    var sSQL="ALTER TABLE " + sTable + " ADD COLUMN " + sFieldName + " INTEGER DEFAULT -1";
    var statement:COpaquePointer = nil
    if sqlite3_prepare_v2(db, sSQL, -1, &statement, nil) != SQLITE_OK {
        println("Failed to prepare statement")
    }else{
        println("field " + sFieldName + " added  to  " + sTable);
        bReturn=true;
    }
    return bReturn;
}

使用此代码,不会添加任何字段,也不会发生错误.有帮助吗？(我想使用本机访问sqlite而没有额外的库)

Answer 1

您只是准备声明,而不是执行它.您需要调用sqlite3_step()和sqlite3_finalize()完成该过程的方法.

func adddbfield(sFieldName:String, sTable:String) -> Bool
{
    var bReturn:Bool = false;
    var sSQL="ALTER TABLE " + sTable + " ADD COLUMN " + sFieldName + " INTEGER DEFAULT -1";
    var statement:COpaquePointer = nil
    if sqlite3_prepare_v2(db, sSQL, -1, &statement, nil) != SQLITE_OK
    {
        println("Failed to prepare statement")
    }
    else
    {
        if sqlite3_step(statement) == SQLITE_DONE
        {
           println("field " + sFieldName + " added  to  " + sTable);
        }
        sqlite3_finalize(statement);
        bReturn=true;
    }
    return bReturn;
}