外部表常规控制命令External table general control commands

有关外部表的概述,请参阅外部表See external tables for an overview of external tables. 以下命令与任何外部表(任何类型)相关。The following commands are relevant to any external table (of any type).

.show external tables.show external tables

语法:Syntax:

.show external tables.show external tables

.show external table TableName.show external table TableName

输出Output

输出参数Output parameter 类型Type 说明Description
TableNameTableName stringstring 外部表的名称Name of external table
TableTypeTableType stringstring 外部表的类型Type of external table
文件夹Folder stringstring 表的文件夹Table's folder
DocStringDocString stringstring 用来记录表的字符串String documenting the table
属性Properties stringstring 表的 JSON 序列化属性(特定于表的类型)Table's JSON serialized properties (specific to the type of table)

示例:Examples:

.show external tables
.show external table T
TableNameTableName TableTypeTableType 文件夹Folder DocStringDocString 属性Properties
TT BlobBlob ExternalTablesExternalTables DocsDocs {}

.show external table schema.show external table schema

语法:Syntax:

.show external table TableName schema as (json | csl).show external table TableName schema as (json | csl)

.show external table TableName cslschema.show external table TableName cslschema

输出Output

输出参数Output parameter 类型Type 说明Description
TableNameTableName stringstring 外部表的名称Name of external table
架构Schema stringstring JSON 格式的表架构The table schema in a JSON format
DatabaseNameDatabaseName stringstring 表的数据库名称Table's database name
文件夹Folder stringstring 表的文件夹Table's folder
DocStringDocString stringstring 用来记录表的字符串String documenting the table

示例:Examples:

.show external table T schema as JSON
.show external table T schema as CSL
.show external table T cslschema

输出:Output:

json:json:

TableNameTableName 架构Schema DatabaseNameDatabaseName 文件夹Folder DocStringDocString
TT {"Name":"ExternalBlob",{"Name":"ExternalBlob",
"Folder":"ExternalTables","Folder":"ExternalTables",
"DocString":"Docs","DocString":"Docs",
"OrderedColumns":[{"Name":"x","Type":"System.Int64","CslType":"long","DocString":""},{"Name":"s","Type":"System.String","CslType":"string","DocString":""}]}"OrderedColumns":[{"Name":"x","Type":"System.Int64","CslType":"long","DocString":""},{"Name":"s","Type":"System.String","CslType":"string","DocString":""}]}
DBDB ExternalTablesExternalTables DocsDocs

csl:csl:

TableNameTableName 架构Schema DatabaseNameDatabaseName 文件夹Folder DocStringDocString
TT x:long,s:stringx:long,s:string DBDB ExternalTablesExternalTables DocsDocs

.drop external table.drop external table

语法:Syntax:

.drop external table TableName [ifexists].drop external table TableName [ifexists]

输出Output

返回已删除表的属性。Returns the properties of the dropped table. 有关详细信息,请参阅 .show external tablesFor more information, see .show external tables.

示例:Examples:

.drop external table ExternalBlob
TableNameTableName TableTypeTableType 文件夹Folder DocStringDocString 架构Schema 属性Properties
TT BlobBlob ExternalTablesExternalTables DocsDocs [{ "Name": "x", "CslType": "long"},[{ "Name": "x", "CslType": "long"},
{ "Name": "s", "CslType": "string" }]{ "Name": "s", "CslType": "string" }]
{}

后续步骤Next steps