Selections

A structure can be selected from, to obtain one of its <#3906#>fields<#3906#> (which in its turn may be a row, a structure or a simple value).

(315,040)<#4641#> (000,030)<#4531#>selection<#4531#> 192 (000,010)<#4532#>(1,0)<#3908#>030<#3908#><#5477#>#tex2html_wrap7271#(060,010)<#5478#>primary<#5478#><#5477#> (1,0)<#3911#>030<#3911#> <#5484#>(010,010)<#5487#>.<#5487#><#5484#> (010,010) (1,0)<#3914#>030<#3914#><#5489#>#tex2html_wrap7281#(060,010)<#5490#>field-name<#5490#><#5489#> (1,0)<#3917#>030<#3917#><#4532#> 193 <#4641#>

The <#3918#>primary<#3918#> must yield a structure, one of whose <#3919#>fields<#3919#> has the <#3920#>field-name<#3920#> as name. The type of the <#3921#>selection<#3921#> is the type of the field yielded. As is the case for the <#3922#>subscription<#3922#>, the <#3923#>selection<#3923#> inherits the access attribute of its <#3924#>primary<#3924#>.