C# 封装 System.Data.SQLite

参考1:

关于如何使用System.Data.SQLite的入门：

http://www.dreamincode.net/forums/topic/157830-using-sqlite-with-c%23/

 

using System;
using System.Collections.Generic;
using System.Data;
using System.Data.SQLite;
using System.Globalization;
using System.Linq;
using System.Windows.Forms;

namespace Simple_Disk_Catalog
{
    public class SQLiteDatabase
    {
        String DBConnection;

        private readonly SQLiteTransaction _sqLiteTransaction;

        private readonly SQLiteConnection _sqLiteConnection;

        private readonly bool _transaction;

        /// <summary>
        ///     Default Constructor for SQLiteDatabase Class.
        /// </summary>
        /// <param name="transaction">Allow programmers to insert, update and delete values in one transaction</param>
        public SQLiteDatabase(bool transaction = false)
        {
            _transaction = transaction;
            DBConnection = "Data Source=recipes.s3db";
            if (transaction)
            {
                _sqLiteConnection = new SQLiteConnection(DBConnection);
                _sqLiteConnection.Open();
                _sqLiteTransaction = _sqLiteConnection.BeginTransaction();
            }
        }

        /// <summary>
        ///     Single Param Constructor for specifying the DB file.
        /// </summary>
        /// <param name="inputFile">The File containing the DB</param>
        public SQLiteDatabase(String inputFile)
        {
            DBConnection = String.Format("Data Source={0}", inputFile);
        }

        /// <summary>
        ///     Commit transaction to the database.
        /// </summary>
        public void CommitTransaction()
        {
            _sqLiteTransaction.Commit();
            _sqLiteTransaction.Dispose();
            _sqLiteConnection.Close();
            _sqLiteConnection.Dispose();
        }

        /// <summary>
        ///     Single Param Constructor for specifying advanced connection options.
        /// </summary>
        /// <param name="connectionOpts">A dictionary containing all desired options and their values</param>
        public SQLiteDatabase(Dictionary<String, String> connectionOpts)
        {
            String str = connectionOpts.Aggregate("", (current, row) => current + String.Format("{0}={1}; ", row.Key, row.Value));
            str = str.Trim().Substring(0, str.Length - 1);
            DBConnection = str;
        }

        /// <summary>
        ///     Allows the programmer to create new database file.
        /// </summary>
        /// <param name="filePath">Full path of a new database file.</param>
        /// <returns>true or false to represent success or failure.</returns>
        public static bool CreateDB(string filePath)
        {
            try
            {
                SQLiteConnection.CreateFile(filePath);
                return true;
            }
            catch (Exception e)
            {
                MessageBox.Show(e.Message, e.GetType().ToString(), MessageBoxButtons.OK, MessageBoxIcon.Error);
                return false;
            }
        }

        /// <summary>
        ///     Allows the programmer to run a query against the Database.
        /// </summary>
        /// <param name="sql">The SQL to run</param>
        /// <param name="allowDBNullColumns">Allow null value for columns in this collection.</param>
        /// <returns>A DataTable containing the result set.</returns>
        public DataTable GetDataTable(string sql, IEnumerable<string> allowDBNullColumns = null)
        {
            var dt = new DataTable();
            if (allowDBNullColumns != null)
                foreach (var s in allowDBNullColumns)
                {
                    dt.Columns.Add(s);
                    dt.Columns[s].AllowDBNull = true;
                }
            try
            {
                var cnn = new SQLiteConnection(DBConnection);
                cnn.Open();
                var mycommand = new SQLiteCommand(cnn) {CommandText = sql};
                var reader = mycommand.ExecuteReader();
                dt.Load(reader);
                reader.Close();
                cnn.Close();
            }
            catch (Exception e)
            {
                throw new Exception(e.Message);
            }
            return dt;
        }

        public string RetrieveOriginal(string value)
        {
            return
                value.Replace("&amp;", "&").Replace("&lt;", "<").Replace("&gt;", "<").Replace("&quot;", "\"").Replace(
                    "&apos;", "'");
        }

        /// <summary>
        ///     Allows the programmer to interact with the database for purposes other than a query.
        /// </summary>
        /// <param name="sql">The SQL to be run.</param>
        /// <returns>An Integer containing the number of rows updated.</returns>
        public int ExecuteNonQuery(string sql)
        {
            if (!_transaction)
            {
                var cnn = new SQLiteConnection(DBConnection);
                cnn.Open();
                var mycommand = new SQLiteCommand(cnn) {CommandText = sql};
                var rowsUpdated = mycommand.ExecuteNonQuery();
                cnn.Close();
                return rowsUpdated;
            }
            else
            {
                var mycommand = new SQLiteCommand(_sqLiteConnection) { CommandText = sql };
                return mycommand.ExecuteNonQuery();
            }
        }

        /// <summary>
        ///     Allows the programmer to retrieve single items from the DB.
        /// </summary>
        /// <param name="sql">The query to run.</param>
        /// <returns>A string.</returns>
        public string ExecuteScalar(string sql)
        {
            if (!_transaction)
            {
                var cnn = new SQLiteConnection(DBConnection);
                cnn.Open();
                var mycommand = new SQLiteCommand(cnn) {CommandText = sql};
                var value = mycommand.ExecuteScalar();
                cnn.Close();
                return value != null ? value.ToString() : "";
            }
            else
            {
                var sqLiteCommand = new SQLiteCommand(_sqLiteConnection) { CommandText = sql };
                var value = sqLiteCommand.ExecuteScalar();
                return value != null ? value.ToString() : "";
            }
        }

        /// <summary>
        ///     Allows the programmer to easily update rows in the DB.
        /// </summary>
        /// <param name="tableName">The table to update.</param>
        /// <param name="data">A dictionary containing Column names and their new values.</param>
        /// <param name="where">The where clause for the update statement.</param>
        /// <returns>A boolean true or false to signify success or failure.</returns>
        public bool Update(String tableName, Dictionary<String, String> data, String where)
        {
            String vals = "";
            Boolean returnCode = true;
            if (data.Count >= 1)
            {
                vals = data.Aggregate(vals, (current, val) => current + String.Format(" {0} = '{1}',", val.Key.ToString(CultureInfo.InvariantCulture), val.Value.ToString(CultureInfo.InvariantCulture)));
                vals = vals.Substring(0, vals.Length - 1);
            }
            try
            {
                ExecuteNonQuery(String.Format("update {0} set {1} where {2};", tableName, vals, where));
            }
            catch
            {
                returnCode = false;
            }
            return returnCode;
        }

        /// <summary>
        ///     Allows the programmer to easily delete rows from the DB.
        /// </summary>
        /// <param name="tableName">The table from which to delete.</param>
        /// <param name="where">The where clause for the delete.</param>
        /// <returns>A boolean true or false to signify success or failure.</returns>
        public bool Delete(String tableName, String where)
        {
            Boolean returnCode = true;
            try
            {
                ExecuteNonQuery(String.Format("delete from {0} where {1};", tableName, where));
            }
            catch (Exception fail)
            {
                MessageBox.Show(fail.Message, fail.GetType().ToString(), MessageBoxButtons.OK, MessageBoxIcon.Error);
                returnCode = false;
            }
            return returnCode;
        }

        /// <summary>
        ///     Allows the programmer to easily insert into the DB
        /// </summary>
        /// <param name="tableName">The table into which we insert the data.</param>
        /// <param name="data">A dictionary containing the column names and data for the insert.</param>
        /// <returns>returns last inserted row id if it's value is zero than it means failure.</returns>
        public long Insert(String tableName, Dictionary<String, String> data)
        {
            String columns = "";
            String values = "";
            String value;
            foreach (KeyValuePair<String, String> val in data)
            {
                columns += String.Format(" {0},", val.Key.ToString(CultureInfo.InvariantCulture));
                values += String.Format(" '{0}',", val.Value);
            }
            columns = columns.Substring(0, columns.Length - 1);
            values = values.Substring(0, values.Length - 1);
            try
            {
                if (!_transaction)
                {
                    var cnn = new SQLiteConnection(DBConnection);
                    cnn.Open();
                    var sqLiteCommand = new SQLiteCommand(cnn)
                                        {
                                            CommandText =
                                                String.Format("insert into {0}({1}) values({2});", tableName, columns,
                                                              values)
                                        };
                    sqLiteCommand.ExecuteNonQuery();
                    sqLiteCommand = new SQLiteCommand(cnn) { CommandText = "SELECT last_insert_rowid()" };
                    value = sqLiteCommand.ExecuteScalar().ToString();
                }
                else
                {
                    ExecuteNonQuery(String.Format("insert into {0}({1}) values({2});", tableName, columns, values));
                    value = ExecuteScalar("SELECT last_insert_rowid()");
                }
            }
            catch (Exception fail)
            {
                MessageBox.Show(fail.Message, fail.GetType().ToString(), MessageBoxButtons.OK, MessageBoxIcon.Error);
                return 0;
            }
            return long.Parse(value);
        }

        /// <summary>
        ///     Allows the programmer to easily delete all data from the DB.
        /// </summary>
        /// <returns>A boolean true or false to signify success or failure.</returns>
        public bool ClearDB()
        {
            try
            {
                var tables = GetDataTable("select NAME from SQLITE_MASTER where type='table' order by NAME;");
                foreach (DataRow table in tables.Rows)
                {
                    ClearTable(table["NAME"].ToString());
                }
                return true;
            }
            catch
            {
                return false;
            }
        }

        /// <summary>
        ///     Allows the user to easily clear all data from a specific table.
        /// </summary>
        /// <param name="table">The name of the table to clear.</param>
        /// <returns>A boolean true or false to signify success or failure.</returns>
        public bool ClearTable(String table)
        {
            try
            {
                ExecuteNonQuery(String.Format("delete from {0};", table));
                return true;
            }
            catch
            {
                return false;
            }
        }

        /// <summary>
        ///     Allows the user to easily reduce size of database.
        /// </summary>
        /// <returns>A boolean true or false to signify success or failure.</returns>
        public bool CompactDB()
        {
            try
            {
                ExecuteNonQuery("Vacuum;");
                return true;
            }
            catch (Exception)
            {
                return false;
            }
        }
    }
}

参考2:

关于如何正确使用System.Data.SQLite提高性能

SQLite .NET performance, how to speed up things?

You definitely need a transaction. If you don't, SQLite starts its own transaction for every insert command so you're effectively doing 86000 transactions as is.

It looks you're also opening and closing the connection each time, along with resetting the CommandText each time. This is unnecessary and doubtless slowing you down, it'll go much faster if you:

• Open the connection once
• Build the command once , adding the parameters to it once.
• Start the transaction
• Loop through, changing the parameter values only before calling ExecuteNonQuery
• Commit the transaction.
• Close the connection.

I think you could reduce your 20 minutes down to just a few seconds this way.

Edit: this is what I mean:

public void InsertItems()
{
    SQLiteConnection connection  = new SQLiteConnection(SomeConnectionString);
    SQLiteCommand command = connection.CreateCommand();
    SQLiteTransaction transaction = connection.BeginTransaction();

    command.CommandText = "INSERT OR IGNORE INTO Result "
+ "(RunTag, TopicId, DocumentNumber, Rank, Score) " +
  "VALUES (@RunTag, @TopicId, @DocumentNumber, @Rank, @Score)";

    command.Parameters.AddWithValue("@RunTag", "");
    command.Parameters.AddWithValue("@TopicId", "");
    command.Parameters.AddWithValue("@DocumentNumber", "");
    command.Parameters.AddWithValue("@Rank", "");
    command.Parameters.AddWithValue("@Score", "");

    foreach ( /* item to loop through and add to db */ )
    {
        InsertResultItem(runTag, topicId, documentNumber, rank, score, command);
    }

    transaction.Commit();
    command.Dispose();
    connection.Dispose();
}

public int InsertResultItem(string runTag, int topicId, string documentNumber, int rank, double score, SQLiteCommand command)
{
    command.Parameters["@RunTag"].Value = runTag;
    command.Parameters["@TopicId"].Value = topicId;
    command.Parameters["@DocumentNumber"].Value = documentNumber;
    command.Parameters["@Rank"].Value = rank;
    command.Parameters["@Score"].Value = score;
    return command.ExecuteNonQuery();
}

It only uses one connection, one transaction and one command, so all you're changing is the parameter values each time. 

 

我自己实现的一个简易版本：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Data.SQLite;

namespace Utility
{
    /*Multithread safety: No!*/
    public class SQLiteDB
    {
        private SQLiteConnection    m_db_conn;
        private SQLiteTransaction    m_transaction;
        private bool                m_is_transaction;
        private SQLiteCommand        m_transaction_cmd;

        public SQLiteDB()
        {
            m_is_transaction = false;
        }

        public SQLiteDB(string db_path)
        {
            m_is_transaction = false;
            m_db_conn = new SQLiteConnection(string.Format("Data Source={0}", db_path));
            m_db_conn.Open();
        }
        public void Open(string db_path)
        {
            m_db_conn = new SQLiteConnection(string.Format("Data Source={0}", db_path));
            m_db_conn.Open();
        }
        public void Close()
        {
            if (m_db_conn.State != System.Data.ConnectionState.Closed)
            {
                m_db_conn.Close();
                m_db_conn.Dispose();
            }
            if (null != m_transaction_cmd)
            {
                m_transaction_cmd.Dispose();
            }
        }

        public void BeginTransaction()
        {
            m_is_transaction = true;
            m_transaction_cmd = m_db_conn.CreateCommand();
            m_transaction = m_db_conn.BeginTransaction();
        }

        public void Commit()
        {
            if (m_is_transaction)
            {
                m_transaction.Commit();
                m_transaction_cmd.Dispose();
                m_is_transaction = false;
            }
        }

        public void Rollback()
        {
            if (m_is_transaction)
            {
                m_transaction.Rollback();
                m_transaction_cmd.Dispose();
                m_is_transaction = false;
            }
        }

        public int ExecuteNonQuery(string non_query_sql)
        {
            if (!m_is_transaction)
            {
                SQLiteCommand sql_cmd = new SQLiteCommand(m_db_conn);
                sql_cmd.CommandText = non_query_sql;
                return sql_cmd.ExecuteNonQuery();
            }
            else
            {
                m_transaction_cmd.CommandText = non_query_sql;
                return m_transaction_cmd.ExecuteNonQuery();
            }
        }
    }
}