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Navigation: Linkar CLIENTS > Client Functions

Select, Select_Text, SelectAsync, SelectAsync_Text

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Executes a query in the database, synchronously or asynchronously.

 

 

* hasError

(only C)

BOOL*

 

Only in C functions: bool pointer used in the C functions that indicates the return of the function is a system error and must be communicated to the Linkar SERVER

 

* callback

OperationAsyncCallbackString

OperationAsyncCallbackLkData

OperationAsyncCallbackClass

ArrayList

 

 

Return type in asynchronous methods. For further information see ASYNCHRONOUS CALLS

* credentialsOptions

CredentialsOptions

char*

 

 

Object that defines the necessary data to access the database: Username, Password, EntryPoint, Language, FreeText. In the C Direct Functions, it is a char*

* connectionInfo

(only C)

char*

 

Only in C Persistent Functions: string that is returned by the Login function and contains all the necessary connection data. This data is necessary in persistent functions.

* filename

string

char*

 

 

File name being selected.
For example LK.ORDERS

selectClause

 

string

char*

 

fragment of the phrase that indicates the selection condition

For example WITH CUSTOMER = '1'

 

sortClause

 

string

char*

 

fragment of the phrase that indicates the selection order. If there is a selection rule Linkar will execute a SSELECT, otherwise Linkar will execute a SELECT

For example BY CUSTOMER

dictClause

 

string

char*

 

A list of dictionary definitions to read, separated by space. If dictionary IDs are not indicated the function will return entire items.

For example CUSTOMER DATE ITEM

preSelectClause

 

string

char*

 

Optional statement to execute before the main Select. More details below.

selectOptions

SelectOptions

char*

 

null

Nothing

 

Object that defines options including pagination and LkData fields to return

outputStringType

enum DataFormat.TYPE

typedef uint8_t DataFormatTYPE;

 

DataFormat.TYPE.MV

Format of the data to be returned: MV, XML, XML_DICT, XML_JSCH, JSON, JSON_DICT, JSON_SCH.

customVars

string

char*

 

This is a free text field to send in the transaction. If not empty, subroutine SUB.LK.MAIN.CONTROL.CUSTOM will be called. Add custom code to that subroutine to define special behaviours for some or all transactions.

 

receiveTimeout

Numeric

 

-1

0

 

This is the maximum time in seconds that the client will wait for a response. Use 0 for no timeout. This is a function-specific override : -1 in a Persistent function defaults back to the timeout defined in the LinkarClt constructor.

 

This function can generate exceptions.

In COM assemblies, a return value of type String will contain an error message if an error occurs when performing the operation.

 

Asynchronous calls are not yet available for C-based Client libraries including C, JavaScript, PHP, and Python.

 

In the preSelectClause Option these operations can be carried out before executing the Select statement:

 

•Previously call to a saved list with the GET.LIST command to use it in the Main Select input

 

•Make a previous Select to use the result as the Main Select input, with the SELECT or SSELECT commands. In this case the entire sentence must be indicated in the PreselectClause.

For example:SSELECT LK.ORDERS WITH CUSTOMER ='1'

 

•Exploit a Main File index to use the result as a Main Select input, with the SELECTINDEX command. The syntax for all the databases is SELECTINDEX index.name.value

For example SELECTINDEX ITEM,"101691"

 

 

       Select. Persistent Functions

       Select. Direct Functions

       SelectAsync. Persistent Functions

       SelectAsync. Direct Functions

by Kosday Solutions