以上最重要的一步，就是将DataTable转为数组的数组表示，即object[][]，前数组的上标是列的个数，后数组是行的个数，因此循环Columns将后数组作为Parameter的值，也就是说，参数的值是一个数组。而insert语句与一般的插入语句没有什么不一样。
三、SQLite数据批量插入
SQLite的批量插入只需开启事务就可以了，这个具体的原理不得而知。
public sealed class SQLiteBatcher : IBatcherProvider
{
/// <summary>
/// 获取或设置提供者服务的上下文。
/// </summary>
public ServiceContext ServiceContext { get; set; }
/// <summary>
/// 将 <see cref="DataTable"/> 的数据批量插入到数据库中。
/// </summary>
/// <param name="dataTable">要批量插入的 <see cref="DataTable"/>。</param>
/// <param name="batchSize">每批次写入的数据量。</param>
public void Insert(DataTable dataTable, int batchSize = 10000)
{
Checker.ArgumentNull(dataTable, "dataTable");
if (dataTable.Rows.Count == 0)
{
return;
}
using (var connection = ServiceContext.Database.CreateConnection())
{
DbTransaction transcation = null;
try
{
connection.TryOpen();
transcation = connection.BeginTransaction();
using (var command = ServiceContext.Database.Provider.DbProviderFactory.CreateCommand())
{
if (command == null)
{
throw new BatcherException(new ArgumentException("command"));
}
command.Connection = connection;
command.CommandText = GenerateInserSql(ServiceContext.Database, dataTable);
if (command.CommandText == string.Empty)
{
return;
}
var flag = new AssertFlag();
dataTable.EachRow(row =>
{
var first = flag.AssertTrue();
ProcessCommandParameters(dataTable, command, row, first);
command.ExecuteNonQuery();
});
}
transcation.Commit();
}
catch (Exception exp)
{
if (transcation != null)
{
transcation.Rollback();
}
throw new BatcherException(exp);
}
finally
{
connection.TryClose();
}
}
}
private void ProcessCommandParameters(DataTable dataTable, DbCommand command, DataRow row, bool first)
{
for (var c = 0; c < dataTable.Columns.Count; c++)
{
DbParameter parameter;
//首次创建参数，是为了使用缓存
if (first)
{
parameter = ServiceContext.Database.Provider.DbProviderFactory.CreateParameter();
parameter.ParameterName = dataTable.Columns[c].ColumnName;
command.Parameters.Add(parameter);
}
else
{
parameter = command.Parameters[c];
}
parameter.Value = row[c];
}
}
/// <summary>
/// 生成插入数据的sql语句。
/// </summary>
/// <param name="database"></param>
/// <param name="table"></param>
/// <returns></returns>
private string GenerateInserSql(IDatabase database, DataTable table)
{
var syntax = database.Provider.GetService<ISyntaxProvider>();
var names = new StringBuilder();
var values = new StringBuilder();
var flag = new AssertFlag();
table.EachColumn(column =>
{
if (!flag.AssertTrue())
{
names.Append(",");
values.Append(",");
}
names.Append(DbUtility.FormatByQuote(syntax, column.ColumnName));
values.AppendFormat("{0}{1}", syntax.ParameterPrefix, column.ColumnName);
});
return string.Format("INSERT INTO {0}({1}) VALUES ({2})", DbUtility.FormatByQuote(syntax, table.TableName), names, values);
}
}
