SQL C#WPF查询已展开

我在这里得到了一个查询的答案SQL Select All Without Values in Another Table。

我刚刚被要求集成来自另一个数据库的数据。这就是我现在所拥有的。

            string _loanSubcontractor = TableNames.Default.LoansSubcontractors;
            string _loanPacific = TableNames.Default.LoansPacific;
            string _tools = TableNames.Default.Tools;
            string _selectStatement = " SELECT [Tools].[Type], [Tools].[Brand], [Tools].[Serial], [Tools].[Year], [Tools].[Code] ";
            string _groupBy = " GROUP BY [Tools].[Type], [Tools].[Brand], [Tools].[Serial], [Tools].[Year], [Tools].[Code], [Tools].[Working] ";
            string _searchItems = " ([Tools].Code LIKE @toolSerial OR [Tools].Serial LIKE @toolSerial) AND ([Tools].[Working] = 'True' OR [Tools].[Working] IS NULL) ";
            SqlConnection myConnection = new SqlConnection(Connection.Default.ConnectionString);
            //Checks the main tool information 
            myConnection.Open();
            SqlCommand getTool = new SqlCommand(
                _selectStatement + "FROM [" + _tools + "] LEFT OUTER JOIN [" + _loanSubcontractor + "] ON " +
                _tools + ".code = [" + _loanSubcontractor + "].ToolCode FULL JOIN [" + _loanPacific + "] ON " + _tools + ".Code = " +
                _loanPacific + ".ToolCode WHERE [" + _loanSubcontractor + "].ToolCode IS NULL AND [" + _loanPacific + "].ToolCode IS NULL AND (" + _searchItems + ")" +
                "UNION " +
            _selectStatement + " FROM [" + _loanSubcontractor + "] INNER JOIN " + _tools + " ON " + _tools + ".Code = [" + _loanSubcontractor + "].ToolCode  " +
                "INNER JOIN " + _loanPacific + " ON " + _loanPacific + ".ToolCode = " + _tools + ".Code " + _groupBy +
                "HAVING (COUNT(" + _loanSubcontractor + ".ReturnDate) = COUNT(*) OR COUNT(" + _loanPacific + ".ReturnDate) = COUNT(*)) " +
                " AND " + _searchItems, myConnection);
            getTool.Parameters.Add("@toolSerial", SqlDbType.NVarChar).Value = "%" + toolSerial + "%";

我有两个贷款表（一个用于员工，一个用于分包商），因为属性名称不同，数据类型也不同。从本质上讲，我需要检查该工具是否正常工作，并且该工具在任何一个贷款表中都没有被出租（如返回日期为空所示）。这两张表中可能有也可能没有贷款。

另外，有人能为我提供一个链接，展示C#中SQL的良好格式技术吗？