Sybase float column read as double by AseDataReader

[alfhv]

I have a SyBase DB table with field of type "float", so I have declared a C# backend field of type "float" also.

When I execute ExecuteReader(sqlQuery), in the retourned AseDataReader class, the column type of field is "double".
When converting this double value to backend "float" field I have precission loss.

How can I force AseDataReader to map column to "float" type as defined in DB ??

Environment

• .NET Core version 3.1
• AdoNetCore.AseClient : 0.19.2

[alfhv]

Please check on this issue and let me know if we are in correct path: linq2db/linq2db#3183

[Ju42]

Hello, I might be missing some informations but from what I can understand you're trying to use the GetFloat method of the AseDataReader class ?

if yes then you have 2 cases:

1. the column you're dealing with is a float with a default precision strictly below 16: the your float is actually stored as a real (see https://infocenter-archive.sybase.com/help/topic/com.sybase.help.ase_15.0.blocks/blocks.pdf page 17, "Range, precision and storage size")
2. the column you're dealing with is a float with a default precision greater or equal to 16 then your float is actually stored as a double

Now from my understanding of this driver implementation if you are in the first case then it will consider the value as TDS_FLT4 leading to being represented as a float while in the second case the value will be considered as TDS_FLT8 and will be represented as a double. Then if you call the GetFloat method on the second case you'll get a double that is then converted to a float.