Unity sqlite notes

Development environment Unity2018.4 .net4.x

Target platform pc, android

The reference library is imported into Mono.Data.Sqlite.dll from Editor \ Data \ Mono \ lib \ mono \ 2.0 (System.Data.dll is not required)

Download sqlite.dll libsqlite3.so from the Internet or https://github.com/feigebabata/unityTools/tree/master/SqliteTool/Plugins

1. Link database statement new SqliteConnection ("data source =" + databasePath); // databasePath is the database file path common to all platforms

    IEnumerator Start()
    {
        string databasePath = Path.Combine(Application.persistentDataPath,"main.db");
        if(!File.Exists(databasePath))
        {
            string copyPath = Path.Combine(Application.streamingAssetsPath,"main.db");
            UnityWebRequest uwr = new UnityWebRequest(copyPath);
            uwr.downloadHandler = new DownloadHandlerFile(databasePath);
            yield return uwr.SendWebRequest();
            if(uwr.isHttpError || uwr.isNetworkError)
            {
                log(uwr.error);
            }

        }
        // string databasePath = Path.Combine(Application.streamingAssetsPath,"main.db");
        connection = new SqliteConnection("data source = "+databasePath);
        connection.Open();
        command = connection.CreateCommand();
        Debug.Log(connection.Database);
        // command.CommandText = "insert into Test2(Age,Name) values(66,'baba')";
        // command.ExecuteReader();
        // seletcAllTab();
        yield return null;
    }

2. Total number of database tables: string sql = "select count (*) from sqlite_master";

3. Whether the table "Test1" exists

string sql = "select count(*) from sqlite_master where type='table' and name='Test1'";
command.CommandText = sql;
Debug.Log(command.ExecuteScalar());

4. Table creation: "create table table name (field 1 type, field 2 type)"

5. C # Sqlite type conversion   can be written without conversion: "create table Data2 (Name String, ID Int32)"

    string CS2DB(Type type)
    {
        string result = "Text";
        if(type==typeof(Int32))
        {
            result = "Int";
        }
        else if (type == typeof(String))
        {
            result = "Text";
        }
        else if (type == typeof(Single))
        {
            result = "FLOAT";
        }
        else if (type == typeof(Boolean))
        {
            result = "Bool";
        }
        return result;
    }

 

6. Drop the table "Test2": string sql = "drop table Test2";

7. Add data: "insert into table name (field 1, field 2) values ​​(data 1, data 2)"

8. Update data: "update table name set update field 1 = update data 1 where field 2 = data 2"

9. Delete data: "delete from table name where field 1 = data 2"

10. Query data: "select * from table name where field 1 = data 1"

    void Select(string _table)
    {
        string sql = $"select * from {_table}";
        log(sql);
        command.CommandText = sql;
        reader = command.ExecuteReader();
        StringBuilder vals_sb = new StringBuilder();
        while(reader.Read())
        {
            for (int i = 0; i < reader.FieldCount; i++)
            {
                vals_sb.AppendFormat("{0}:{1},",reader.GetName(i),reader.GetValue(i));
            }
            log(vals_sb.ToString());
            vals_sb.Clear();
        }
        command.Dispose();
    }