SQL將列轉換爲浮動在where子句中

Question

我在我的數據庫表中有這一列及其字符串。我沒有做這個表，我不能改變數據類型。

但是我需要將它轉換爲我的where子句中的float，以便我可以將它與浮點數進行比較。

我已經試過了鑄造我的專欄，爲float：

sql += " AND CAST (ec.bedrooms as float) <= " + id.beds.Max().Split('-')[1] + " AND CAST (ec.bedrooms as float) >= " + id.beds.Min().Split('-')[0]; 

，但沒有工作，因爲我得到這個錯誤：

An error occurred while reading from the store provider's data reader. See the inner exception for details 

我在做什麼錯？

這裏是正在爲部分

AND CAST (ec.bedrooms as float) <= 3 AND CAST (ec.bedrooms as float) >= 2 

"InnerException":{"Message":"An error has occurred.","ExceptionMessage":"Error converting data type nvarchar to float.","ExceptionType":"System.Data.SqlClient.SqlException","StackTrace":" at System.Data.SqlClient.SqlConnection.OnError(SqlException exception, Boolean breakConnection, Action`1 wrapCloseInAction)\r\n at System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection, Action`1 wrapCloseInAction)\r\n at System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj, Boolean callerHasConnectionLock, Boolean asyncClose)\r\n at System.Data.SqlClient.TdsParser.TryRun(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj, Boolean& dataReady)\r\n at System.Data.SqlClient.SqlDataReader.TryHasMoreRows(Boolean& moreRows)\r\n at System.Data.SqlClient.SqlDataReader.TryReadInternal(Boolean setTimeout, Boolean& more)\r\n at System.Data.SqlClient.SqlDataReader.Read()\r\n at System.Data.Entity.Core.Common.Internal.Materialization.Shaper`1.StoreRead()"}} 

Answer 1

看起來你ec.bedrooms產生什麼是具有非數字值......您可以檢查象下面這樣：

sql += " AND CAST (iif(isnumeric(ec.bedrooms)>0,ec.bedrooms,null) as float) <= " + id.beds.Max().Split('-')[1] + " AND 
CAST (iif(isnumeric(ec.bedrooms)>0,ec.bedrooms,null) as float) >= " + id.beds.Min().Split('-')[0];