• 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
  • 相关阅读:
    unnitest简单场景应用
    接口基础之request
    docker常用命令
    管理之心理学
    管理团队挑战和提升
    如何留下核心成员
    管理之面试技巧
    复杂接口请求怎样写http请求
    gitlab使用(一)
    不使用AutoLayout快速兼容适配iPhone6/6 Plus
  • 原文地址:https://www.cnblogs.com/geovindu/p/4362406.html
Copyright © 2020-2023  润新知