Data Types

Table 5 through Table 8 list the data types supported by the PSQL ADO.NET Data Provider.

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Table 5 maps the PSQL data types to the .NET Framework types.

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Table 6 maps the data types the data provider uses if only the System.Data.DbType is specified.

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Table 7 maps the data types the data provider uses to infer a data type if neither the provider-specific type nor the System.Data.DbType are provided.

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Table 8 maps the data types the data provider uses when streams are used as inputs to Long data parameters.

Mapping PSQL Data Types to .NET Framework Data Types

Table 5 lists the data types supported by the ADO.NET data provider and how they are mapped to the .NET Framework types. You can use the table to infer the data types that will be used when a DataSet is filled using a DataAdapter.

This table also identifies the proper accessors for accessing the data when a DataReader object is used directly.

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The PSQL Data Type column refers to the native type name.

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The PsqlDbType column refers to the PSQL ADO.NET Data Provider’s type enumeration. Generally, there is a one to one mapping between the native type and the PsqlDbType. The PSQL NUMBER data type, which can be either a decimal or a double, is an exception to this rule.

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The .NET Framework Type column refers to the base data types available in the Framework.

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The .NET Framework Typed Accessor column refers to the method that must be used to access a column of this type when using a DataReader.

Table 5

Mapping of PSQL Data Types

PSQL Data Type

PsqlDbType

.NET Framework Type

.NET Framework Typed Accessor

1 Supported in PSQL 9.5 and higher

2 Depends on the setting of the timetype connect option.

Mapping Parameter Data Types

The type of the parameter is specific to each data provider. The ADO.NET data provider must convert the parameter value to a native format before sending it to the server. The best way for an application to describe a parameter is to use the data provider-specific type enumeration.

In generic programming circumstances, the data provider-specific type may not be available. When no provider-specific DB type has been specified, the data type will be inferred from either the System.Data.DbType or from the .NET Framework type of the parameter’s value.

The ADO.NET data provider uses the following order when inferring the data type of a parameter:

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The data provider uses the provider-specific data type if it has been specified.

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The data provider infers the data type from the System.Data.DbType if it has been specified, but the provider-specific data type has not been specified.

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The data provider infers the data type from the .NET Framework type if neither the provider-specific data type nor the System.Data.DbType have been specified.

Table 6 shows how the data provider infers its types if only the System.Data.DbType is specified.

Table 6

Mapping System.Data.DbTypes to PsqlDbTypes

AnsiStringFixedLength

1 Supported in PSQL v9.5 and higher.

Table 7 shows the mapping that the data provider uses to infer a data type if neither the provider-specific data type nor the System.Data.DbType are provided.

Table 7

Mapping .NET Framework Types to PsqlDbType