Queries messages in an SQL-like style. We get repeated row-like structures by looping over repetitions of groups, segments, or fields. This is a very advanced class ... maybe too advanced even for you. If you find it confusing, please note that there are simpler ways to get data from a message (like calling its getters or using Terser). LOOPING: You specify the loop points as part of the query. For example you could specify loop point x like this:
x = /.MSH-18(*). The * is replaced by numbers 0, 1, 2, etc. as you loop through the results, so this example would loop through repetitions of MSH-18. If there are multiple loop points, the loops are nested so that each possible combination is returned. Looping stops when none of the fields under a loop point are valued. The name of the loop point ('x' in the example above) is arbitrary. SELECTING FIELDS: The syntax is similar to SQL, except that Terser paths are used in place of table.field. You can use the "as" keyword to give a field a name, like this:
select /.MSH-7 as msg_date. If your field is under a loop point, replace the path up to the loop point with a loop point reference, like this:
select {foo}-1 loop foo = /.PID-3(*) SELECTING ROWS: A "row" is a combination of all selected fields at one iteration. You can filter which rows are returned using a where clause similar to that in SQL. Use exact values or regular expressions, for example:
where {1} like '.*blood.*' or
where {1}/PID-3-1 = '111' Multiple filters can be separated with commas (which mean 'and'). Future versions may support 'or', negation, brackets, etc., but this version doesn't. FULL EXAMPLE: select {pat-id}-1 as id loop pat-id = ./PID-3(*) where {pat-id}-2 = 'mrn' SUBTLETIES OF LOOPING: A loop point can be under another loop point. For example consider the message: MSH|etc.|etc. Z01|one~two|a Z01|three~four|b The query, "select {a}-2, {b} loop a = /Z01(*), b = {a}-1(*)" would return: a one a two b three b four While the query "select {a}-2, {b} loop a = /Z01(*), b = /Z01(1)-1(*)" would return: a one a two b one b two In the first case, one loop point refers to another. In the second case the loops are treated as independent, just as if they referred to different branches of the message. TODO: could support distinct easily by keeping record of rows and comparing each one to previous rows
@author
Bryan Tripp
@version $Revision: 1.1 $ updated on $Date: 2007-02-19 02:24:27 $ by $Author:jamesagnew $