protected T ExecuteScalar <T>(
string sql,
IEnumerable <QueryParameterInfo> parameters = null,
IEnumerable <ParameterValue> parameterValues = null
)
{
T commandResult;
SqlScalarCommand scalarCommand = new SqlScalarCommand(
this.Connection,
sql,
this.GetParameters(parameters, parameterValues)
);
lock (this._tablesLock)
{
scalarCommand.Execute(100);
object sqlResult = scalarCommand.Result;
commandResult = sqlResult == DBNull.Value
? default(T)
: (T)sqlResult;
}
return(commandResult);
}
public static bool TableExists(
SQLiteConnection connection,
string tableName
)
{
bool boolIsTableExists = false;
string query = null;
if (tableName != null)
{
using (connection.OpenWrapper())
{
query = string.Format(
"SELECT COUNT(*) FROM [sqlite_master] m WHERE m.[type] = 'table' AND m.[name] = '{0}'",
tableName
);
SqlScalarCommand command = new SqlScalarCommand(
connection,
query
);
command.Execute(100);
if ((long)command.Result > 0L)
{
boolIsTableExists = true;
}
}
}
return(boolIsTableExists);
}
public long GetMaxRequestId()
{
lock (this.maxRequestLock)
{
if (this.maxRequestCache == null)
{
string sql = string.Format(
"SELECT MAX({0}) FROM [{1}]",
RequestIdFieldName,
TableName
);
using (this.Connection.OpenWrapper())
{
SqlScalarCommand command = new SqlScalarCommand(this.Connection, sql);
command.Execute(100);
object sqlResult = command.Result;
if (sqlResult == DBNull.Value)
{
this.maxRequestCache = 0;
}
else
{
this.maxRequestCache = (Int64)sqlResult;
}
}
}
else
{
this.maxRequestCache++;
}
return(this.maxRequestCache.Value);
}
}
