number of take
The conditions for joining tables after ON
where selection criteria
left outer join
In the left outer join: the conditions of the right table and the association conditions of the two tables are written after on , and the filter conditions of the left table are written after where .
ON must be followed by = to judge the condition and use others to report an error
like:
When querying multiple tables: the data can be fetched separately instead of multiple connections
The connection operation in the database table is to check n*m pieces of data, and the data processing operation in the database table is much slower than the data processing operation between internal tables.
Fetch the numbers to the inner table respectively
According to the conditions, it is finally summarized into the total table. The above picture is similar to the left outer connection
This is equivalent to deleting the row where zsname is empty.
multi-table join
Select table (self-contained table header)
Can be equivalent to multi-select boxes as conditions
When the data length does not match/type does not match
It can be achieved by adding zschool in r_school.
TOP-OF-PAGE (primary form)
Fixed output interface header row
secondary form
background color
Effect
Font color INVERSE
Effect
Basic content of the program
program initialization
Modular
Capturing the field name and value of the double-clicked position of the cursor
When clicking on the header, there are only values but no field names
Implement the click event
The event is to achieve the above
Screen after jump (secondary form)
Do headers in the new screen write syntax.
call status bar
settings button
Set button function
AT USER-COMMAND
form parameter
p_flag does not need to be defined
using p_flag.
It is also equivalent to declaring a variable of type any
using
The change of p_flag (formal parameter) in from will affect the actual parameter
using value
Only the value of p_flag (formal parameter) is used in from and will not affect the actual parameter
changing has the same effect as changing value()
pass the table
tables are specially passed tables and should be placed at the front.
help
Click the keyword and press F1 to display the help document
Select the screen tab
Production Method:
The first step is to create two sub-interface screens
continued
Give pagination name in initial
mytab-prog specifies the program
mytab-dynnr initial interface
mytab-activetab default tab1 subinterface
sy-dynnr interface number.
mytab-activetab activate button (click to change)
Add () to the variable to indicate the value
Upgrade (using internal table to access data)
connection operation
concatenate lv_field lv_fieldname into lv_field separated by '-'.
*用-分格链接 等同于
concatenate lv_field '-' lv_fieldname into lv_field.SY-LSIND form serial number
SY-LSIND = SY-LSIND - 1. Avoid generating multiple interfaces.
SYST Database table for storing sy-system variables
The solution to the invalidation of the double-click event caused by the screen button event
PICK is the double-click function code.
Does not contain the meaning of the button
After this, the download button no longer appears on the screen.
set titlebar is to modify the program properties that is to change the program description
activation required
Dynamic display description
At this time, the description becomes a student information table (there is only one description title in a screen)
SY-LSIND Multiple lists share one screen.
