9.12 Accessing Tables With Sql Statements; Introduction - HEIDENHAIN TNC 620 User Manual

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9.12 Accessing tables with SQL statements

Introduction

If you would like to access numerical or alphanumerical content in
a table or manipulate the table (e.g., rename columns or rows), then
use the available SQL commands.
The syntax of the SQL commands available on the control is strongly
influenced by the SQL programming language but does not conform
with it entirely. In addition, the control does not support the full scope
of the SQL language.
The names of tables and table columns must start with
a letter and must not contain an arithmetic operator
(e.g., +). Due to SQL commands, these characters can
cause problems when data are input or read.
SQL functions can be tested only in the Program
run, single block, Program run, full sequence, and
Positioning with Manual Data Input operating modes.
Read- and write-accesses to individual values in a table
can likewise be carried out using the functions FN 26:
TABOPEN, FN 27: TABWRITE, and FN 28: TABREAD.
Further information: "Freely definable tables", Page 413
HEIDENHAIN recommends that you use SQL functions
instead of FN 26, FN 27, or FN 28 in order to achieve
maximum HDR hard-disk speeds for table applications
and to reduce the amount of computing power used.
The following terms will be used (along with others) below:
"SQL command" refers to the available soft keys
"SQL instructions" describe miscellaneous functions that are
entered manually as part of the syntax
A HANDLE in the syntax identifies a certain transaction (followed
by the parameter for identification)
A result set contains the result of the query
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Programming Q parameters | Accessing tables with SQL statements
HEIDENHAIN | TNC 620 | Klartext Programming User's Manual | 01/2022