The most predominant use of Net.data is for displaying content from the database using SQL select statements.

IMPORTANT - Net.data defaults to using SQL naming convention, which basically means that it uses dot notation instead of a forward slash for qualified names. e.g. QIWS.QCUSTCDT instead of QIWS/QCUSTCDT We will assume Net.data has been configured for SYSTEM naming (forward slashes). Enabling the SYSTEM naming convention requires a Net.data INI file. Refer here, configuring a Net.data INI file to ensure you have SYSTEM naming.

We will choose to display the following file which ships with the system - QIWS/QCUSTCDT - PC Support Customer File Create a source file named sqldemo1 in your Net.data source folder. Enter the following code into the file.
```
%function(dtw_sql) list() {  
  SELECT * FROM QIWS/QCUSTCDT WHERE CDTDUE > 0
%}  
                       
%html(macro) {               
   @list()                      
%}                           
```
The complete source code and be viewed at sqldemo1.

Now run the macro by entering the following url into the browser address line http://mysite/cgi/sqldemo1/macro This should return the following page -

CUSNUM | LSTNAM  | INIT | STREET        | CITY   | STATE | ZIPCOD | CDTLMT | CHGCOD | BALDUE  | CDTDUE |
---------------------------------------------------------------------------------------------------------
 938485 | Johnson | J A  | 3 Alpine Way  | Helen  | GA    | 30545  | 9999   | 2      | 3987.50 | 33.50  |
---------------------------------------------------------------------------------------------------------
 389572 | Stevens | K L  | 208 Snow Pass | Denver | CO    | 80226  | 400    | 1      | 58.75   | 1.50   |
---------------------------------------------------------------------------------------------------------
 475938 | Doe     | J W  | 59 Archer Rd  | Sutter | CA    | 95685  | 700    | 2      | 250.00  | 100.00 |
---------------------------------------------------------------------------------------------------------
 192837 | Lee     | F L  | 5963 Oak St   | Hector | NY    | 14841  | 700    | 2      | 489.50  | .50    |
---------------------------------------------------------------------------------------------------------

You can see that displaying a database file can be accomplished with just a couple of statements using Net.data. The response has been automatically formatted into the default fixed grid format by Net.data. This has been achieved by using a Net.data %function block. Net.data just needs to know the environment in which to execute the function, DTW_SQL, in this case, and the statement to be executed, an SQL select in this case. You can see that the syntax for invoking the function is to place the function name prefixed with the @ token somewhere within the %html block. The function block itself must be defined prior to the %html block. This is because Net.data interprets the source code from the top down, loading up function blocks as it goes, which means a function must have been loaded before Net.data encounters a line with the syntax to execute the function, in this case, @list().

Now we can expand the example to format the response as an HTML table instead of the default grid. We will also restrict the SQL select statement to extract just the first 5 columns of the database table. Replace the DTW_SQL function block with the following function block -

%function(dtw_sql) list() {                                              
  SELECT CUSNUM, LSTNAM, INIT, STREET, CITY                              
  FROM QIWS/QCUSTCDT WHERE CDTDUE > 0                                    
  %report {  <table border="2" cellspacing="2" cellpadding="2"           
              style="border-collapse: collapse; border: solid 1pt black;">
     %row {  <tr>                                                        
                 <td>$(V1)</td>
                 <td>$(V2)</td>                                       
                 <td>$(V3)</td>
                 <td>$(V4)</td>  
                 <td>$(V5)</td>                                      
                 </tr>                                 
     %}      </table>                                                    
  %}                                                                     
%}

The complete source code and be viewed at sqldemo2

Now enter the url into the browser again. This should now return the following page like - SQL Demo Example 2

938485	Johnson	J A	3 Alpine Way	Helen
389572	Stevens	K L	208 Snow Pass	Denver
475938	Doe	J W	59 Archer Rd	Sutter
192837	Lee	F L	5963 Oak St	Hector

The formatting has been achieved with the addition of a %report block within the DTW_SQL function block, in conjunction with a bit of HTML table markup. The %report block contains a nested %row block which gets executed for each row in the database table. Net.data will interpret any lines between the %report block and the %row block as output to be sent to the browser, so this is where the html markup code for the table header goes. The html markup for each table row element goes within the %row block. Notice the presence of dollar variables within the %row block. The dollar sign is Net.data syntax for a substitution variable. Anything that begins with a dollar sign refers to a variable whose value must have already been assigned. Within a %row block, dollar variables whose name begins with V have a predefined meaning. Net.data automatically presents the database column values to the %row block as predefined numbered variables $(V1)......$(V5). In fact, Net.data also presents them as predefined named variables $(V_CUSNUM), $(V_LSTNAM), $(V_INIT), $(V_STREET) and $(V_CITY). You can use whichever variable format that suits you.

Just as $(V1)....etc variables are significant within a %row block, Net.data also provides for $(N1).....etc variables within the section between the %report and %row block. Just as $(V) variables are automatically populated with column values, $(N) variables are populated with column headings. This means we can extend the example to show headings for each column. To achieve this we can insert the following line before the %row block -
```
<tr>
      <$(N1)</td>
      <$(N2)</td>
      <$(N3)</td>
      <$(N4)</td>
      <$(N5)</td>
 </tr>
```
The complete source code and be viewed at sqldemo3

Now enter the url into the browser again. This should now return the following page like - SQL Demo Example 3

CUSNUM	LSTNAM	INIT	STREET	CITY
938485	Johnson	J A	3 Alpine Way	Helen
389572	Stevens	K L	208 Snow Pass	Denver
475938	Doe	J W	59 Archer Rd	Sutter
192837	Lee	F L	5963 Oak St	Hector

You can see that the Net.data has retrieved the column names from the database table. Note that these are not the column headings but the 10 character column names.