PostgreSQL Metadata

 
In this overload first parameter is name of a collection, and second parameter is the array of restrictions to be applied when querying information. These restrictions specify which subset of the collection will be returned. The restrictions can include, for example, the database name (in this case, only collection elements belonging to this database will be returned) or the mask for the name of collection elements (only the elements satisfying this mask will be returned). The quantity and description of restrictions allowed for each metadata collection are represented in the table here. Their number can also be obtained from the return of the GetSchema() method. If the second parameter is null/Nothing, it is ignored.
Instead of specifying the metadata collection name as a string constant, you may use members of System.Data.DbMetaDataCollectionNames and Devart.Data.PostgreSql.PgSqlMetadataCollectionNames as the first GetSchema argument values. The members of these classes are the string fields, each field stores the corresponding metadata collection name. It is recommended to use these fields rather than manually input the collection names manually as the string constants because in case of using these fields, you will find misspellings at compile-time, and intellisense will show you all the available metadata collection names.
GetSchema Method Reference
GetSchema supports two kinds of wildcards: "%" and "_". These special characters behave exactly as in LIKE operator. "%" means zero or more of any characters, "_" means any single character.
When calling the GetSchema method, you can pass all or few of restrictions, applicable to the chosen collection. In the latter case, you have to put "%" wildcard in the place of omitted restriction, if it must be specified before the restriction you want to apply. For example, GetSchema("Casts", new string[] { "%", "%", "date" }) returns list of all casts to type "date". Or, suppose you want to query all functions within a certain schema: GetSchema("Functions", new string[] { "%", "public" }) returns list of all functions in schema public. Note that this collection may accept 8 restrictions, however, you do not need to specify all of them.
The following table provides detailed information on metadata collections that can be retrieved using the GetSchema method, and restrictions that can be applied for them. Some collections may be not supported in older server versions. If you try to get metadata for unsupported collection you will get exception with message "Collection not defined".
Collection Name
Number of restrictions
Remarks
MetaDataCollections 0
Returns this list. Same as using GetSchema() method without parameters.
ReservedWords 0
Lists all reserved words used in the server.
AggregateFunctions 2
GetSchema("AggregateFunctions") returns detailed list of all aggregate functions on the server.
  • The first restriction for this collection is a name of a function. If specified, the method returns all overloads with given name.
  • The second restriction is name of function definer. For example, you can issue "%" as the first restriction, and "postgres" as the second one, to obtain list of functions defined by user "postgres".
Arguments 5
GetSchema("AggregateFunctions") returns the list of the function arguments. The following restrictions may be specified:
  • Schema name
  • Function name
  • User name
  • Type
  • Function OID (for overload functions)
Casts 3
GetSchema("Casts") returns list of casts available on the server.
  • The first restriction for this collection is namespace of a cast.
  • The second restriction is source type for the cast.
  • The third restriction is target type for the cast.
Columns 3
Returns list of columns, their schema, table, type, and some extra information.
  • Restricted by schema name, GetSchema returns columns of all tables within the schema.
  • The second restriction is name of a table that GetSchema method should search in.
  • At last, you can set column name pattern to filter columns by name.
Databases 3
Returns list of databases on the server.
  • The first restriction is a name of a database.
  • The second restriction is definer's name.
  • The last restriction is encoding of the database.
DatasourceInformation 1
Returns information about data sources.
The only restriction is schema name.
Domains 9
Returns list of domains on the server. The restrictions for this collection are the following:
  • Domain name
  • Definer
  • OID type
  • Base type
  • Type length
  • Typmod
  • Number of dimensions
  • Schema name
  • OID
ForeignKeys 4
Returns list of foreign keys on the server. The restrictions for this collection are the following:
  • Key name
  • Schema name
  • Table name
  • OID
Functions 8
Returns list of functions on the server. The following restrictions may be specified:
  • Function name
  • Schema name
  • Definer
  • Language
  • Arguments count
  • Return type OID
  • Return type
  • OID
Groups 1
Lists all groups on the server, including IDs and members.
The only restriction is a group name.
Indexes 4
Returns list of indexes and their details. Restricted by:
  • Index name
  • Schema name
  • Table name
  • OID
Languages 2
Lists all languages on the server.
The first restriction is a language name, the second is OID.
NestedTables 5
Lists nested tables on the server. Restricted by:
  • Table name
  • Schema name
  • Parent table name
  • Parent schema name
  • OID
Operators 2
Returns list of operators allowed on the server.
Restrict it by OID and name.
PrimaryKeys 3
Returns list of primary keys on the server.
  • First restriction is key name.
  • Second is schema name
  • Third is table name
Schemas 2
Returns list of schemas on the server.
  • The first restriction is OID
  • The second restriction is schema name
Tables 4
Returns list of tables on the server. Restrict the collection with:
  • OID
  • Table name
  • Schema name
  • Definer
Triggers 6
Returns list of triggers on the server. Restricted by:
  • OID
  • Trigger name
  • Schema name
  • Definer
  • Language
  • Arguments count
Types 5
Returns list of types on the server. Restricted by:
  • OID
  • Type name
  • Schema name
  • Definer
  • Type Length
Users 1
Lists all users on the server.
When restricted by username, returns information about specific user.
Views 4
Returns list of types on the server. Restricted by:
  • OID
  • View name
  • Schema name
  • Definer

Npgsql 集合：

MetaDataCollections
Restrictions
Databases
Tables
Columns
Views
Users

https://github.com/npgsql/Npgsql/releases/tag/v2.2.4.3

http://npgsql.projects.pgfoundry.org/docs/api/Npgsql.NpgsqlConnection.GetSchema_overloads.html

http://www.codeproject.com/Articles/37154/PostgreSQL-PostGis-Operations

数据类型：

bit System.Int64 1560
varbit System.Int64 1560
bit varying System.Int64 1560
bool System.Boolean 16
boolean System.Boolean 16
smallint System.Int16 21
int System.Int32 23
integer System.Int32 23
int4 System.Int32 23
serial System.Int32 23
serial4 System.Int32 23
bigint System.Int64 20
int8 System.Int64 20
bigserial System.Int64 20
serial8 System.Int64 20
float System.Single 700
real System.Single 700
float4 System.Single 700
double System.Double 701
double precision System.Double 701
decimal System.Decimal 1700
numeric System.Decimal 1700
dec System.Decimal 1700
date System.DateTime 1082
timestamp System.DateTime 1114
timestamptz System.DateTime 1184
time System.TimeSpan 1083
timetz System.TimeSpan 1266
interval System.TimeSpan 1186
char System.String 1042
character System.String 1042
uuid System.Guid 2950
varchar System.String 1043
character varying System.String 1043
text System.String 25
binary System.Byte[] 17
bytea System.Byte[] 17
cidr System.String 29
circle System.String 718
inet System.String 869
line System.String 628
lseg System.String 601
macaddr System.String 829
box System.String 603
path System.String 602
point System.String 600
polygon System.String 604
money System.Double 790

 集合：

MetaDataCollections
ReservedWords
AggregateFunctions
Arguments
Casts
CompositeTypeAttributes
Columns
DataSourceInformation
DataTypes
Databases
Domains
ForeignKeys
ForeignKeyColumns
Functions
Groups
Indexes
Indexcolumns
Languages
NestedTables
Operators
OperatorClasses
PrimaryKeys
Rules
Schemas
Sequences
Tables
Triggers
Types
Users
UserPrivileges
UniqueKeys
Views
Restrictions 
Postgresql  NpgsqlDbType System.DbType Enum .Net System Type
----------  ------------ ------------------ ----------------
int8        Bigint       Int64              Int64
bool        Boolean      Boolean            Boolean
bytea       Bytea        Binary             Byte[]
date        Date         Date               DateTime
float8      Double       Double             Double
int4        Integer      Int32              Int32
money       Money        Decimal            Decimal
numeric     Numeric      Decimal            Decimal
float4      Real         Single             Single
int2        Smallint     Int16              Int16
text        Text         String             String
time        Time         Time               DateTime
timetz      Time         Time               DateTime
timestamp   Timestamp    DateTime           DateTime
timestamptz TimestampTZ  DateTime           DateTime
interval    Interval     Object             TimeSpan
varchar     Varchar      String             String
inet        Inet         Object             IPAddress
bit         Bit          Boolean            Boolean
uuid        Uuid         Guid               Guid
array       Array        Object             Array
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原文地址：https://www.cnblogs.com/geovindu/p/4362406.html