C＃：与OracleDbType等效的Oracle数据类型

Question

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Situation:

I am creating an app in C# that uses Oracle.DataAccess.Client (11g) to do certain operations on a Oracle database with stored procedures. I am aware that there is a certain enum (OracleDbType) that contains the Oracle data types, but I am not sure which one to use for certain types.

Questions:

• What is the equivalent Oracle PL/SQL data type for each enumerated type in the OracleDbType enumeration ?

• There are three types of integer
  (Int16, Int32, Int64) in the OracleDbType... how to know which one to use or are they all
  suppose to work?

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Answer 1

Here's a method to convert C# types to the most common OracleDbTypes

private static OracleDbType GetOracleDbType(object o) 
{
  if (o is string) return OracleDbType.Varchar2;
  if (o is DateTime) return OracleDbType.Date;
  if (o is Int64) return OracleDbType.Int64;
  if (o is Int32) return OracleDbType.Int32;
  if (o is Int16) return OracleDbType.Int16;
  if (o is sbyte) return OracleDbType.Byte;
  if (o is byte) return OracleDbType.Int16;    -- <== unverified
  if (o is decimal) return OracleDbType.Decimal;
  if (o is float) return OracleDbType.Single;
  if (o is double) return OracleDbType.Double;
  if (o is byte[]) return OracleDbType.Blob;

  return OracleDbType.Varchar2;
}

Also, for very large character data values, you may want to use OracleDbType.Clob .

Answer 2

The values of the OracleDbType Enumeration are defined in the documentation. Read the ODP for .NET Developer's Guide .

With regards to choosing between Int16, Int32 and Int64, they are all supposed to work. Choose the one which matches the expected size of your .Net variable: Int16 for values between -32768 and 32767, Int32 for values between -2147483648 and 2147483647, and Int64 for anything larger. There appear to be some funnies relating to converting Ints and PL/SQL data types. Check this blog post by Mark Williams .

Answer 3

Check APC's links out, they are what you are looking for : the mapping is quite straightforward according to the name of the enumeration.

But as you began to notice, there is something tricky about integers. Here is my mapping :

• Int16 : NUMBER(5) .
• Int32 : NUMBER(10) .
• Int64 : NUMBER(19) .

The thing is that if you call GetInt64 on a NUMBER(38) column, you will get an exception even if the value is in the correct range...

Answer 4

NUMBER(1,0) => Boolean

NUMBER(5,0) => Int16.MaxValue == 32767

NUMBER(10,0) => Int32.MaxValue == 2,147,483,647

NUMBER(19,0) => Int64.MaxValue == 9,223,372,036,854,775,807

NUMBER(19,0) => long.MaxValue == 9,223,372,036,854,775,807

Answer 5

For those who wants to know the equivalent of de floating points:

Decimal     Oracle NUMBER type
Double      8-byte FLOAT type

Decimal is the way to go if you used Number in oracle.

As APC pointed: https://docs.oracle.com/cd/B19306_01/win.102/b14307/OracleDbTypeEnumerationType.htm