dc
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A table's metadata columns are named per table - VAR_TXFROM, VAR_TXTO and VAR_PROCESSED in MPE_TABLES hold those names, and they can be anything (the bitemporal demo table uses VER_FROM_DTTM and VER_TO_DTTM). When they exist they are physical columns of the target, so the engine's collision check already refuses a VAR_NM that matches one, whatever it is called. The hard-coded list treated three example names as special: it refused them on tables that use other names, and told the reader something untrue about what is reserved.
104 lines
3.6 KiB
SAS
104 lines
3.6 KiB
SAS
/**
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@file
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@brief Generates the SAS statements that create Data Controller derived variables
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@details Derived (computed) variables are configured in MPE_DERIVED. Each
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row defines one variable, which is created in a DATA step view ahead of the
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filter, so that it can be filtered on in the EDIT screen.
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The engine lives in @sasjs/core as mp_derivedvars - this macro only supplies
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what is specific to Data Controller: the control table name, the bitemporal
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filter that picks the current version of a row, and the list of names that
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belong to the metadata and may not be used as a variable.
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The macro writes the generated statements to a fileref, so that callers can
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compose them into a view:
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%mpe_derived(libds=&libds,dclib=&mpelib,outref=dercode)
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data work.vw_derived / view=work.vw_derived;
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set &libds;
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%include dercode;
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run;
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Alternatively, pass outview= and the macro will build the view itself.
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The filter must be applied by the caller, in the step that reads the view:
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data out;
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set work.vw_derived;
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where %inc filtref;;
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run;
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A WHERE statement applies to the data set named on the SET statement, so it
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cannot reference a variable that is created in the same data step. Applying
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it to the view puts the derived variables on the input, which is what makes
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them filterable.
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Each statement block is of the form:
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attrib REGION length=$21 label='REGION=<expression>' format=$21.;
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REGION = <expression>;
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Type and length are declared by the administrator, so the result is
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deterministic. VAR_LABEL is optional: when it is missing or blank the label
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is the variable name, an equals sign and the expression, otherwise the
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configured label is used as given.
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VAR_DEPS lists every input the expression uses - physical columns and
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derived variables alike. The statements are generated in dependency order,
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so a derived variable may build on another one without a sequence number
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being maintained. A cycle is rejected.
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Semicolons, macro triggers and comments are rejected, so a row can only ever
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be an expression. A derived variable may not reuse the name of a physical
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column, and may not reference itself: an intra-row calculation would imply a
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retained value, which depends on the order rows happen to arrive in.
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<h4> SAS Macros </h4>
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@li mp_derivedvars.sas
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@li mp_abort.sas
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@param [in] libds= The target table (libref.dataset, lib must be assigned)
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@param [in] dclib= The Data Controller control library
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@param [out] outref= (0) Fileref to receive the generated statements
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@param [out] outvars= (work.derived_vars) Dataset of derived variable names
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@param [in] outview= (0) Optional two-level name for the derived view
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@version 9.2
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@author 4GL Apps Ltd
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@copyright 4GL Apps Ltd. This code may only be used within Data Controller
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and may not be re-distributed or re-sold without the express permission of
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4GL Apps Ltd.
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**/
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%macro mpe_derived(libds=,
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dclib=,
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outref=0,
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outvars=work.derived_vars,
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outview=0
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);
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%local reserved;
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/* the only name that has to be refused outright - the metadata columns of the
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target table are physical columns, so the engine's collision check covers
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them whatever MPE_TABLES calls them */
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%let reserved=%str(_____DELETE__THIS__RECORD_____);
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%mp_abort(iftrue= (%length(&libds)=0 or %length(&dclib)=0)
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,mac=&sysmacroname
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,msg=%str(Missing: libds dclib)
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)
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%mp_derivedvars(
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libds=&libds
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,control=&dclib..mpe_derived
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,where=%str(&dc_dttmtfmt lt tx_to and active=1)
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,outref=&outref
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,outvars=&outvars
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,outview=&outview
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,reserved=&reserved
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)
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%mend mpe_derived;
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