How to set the NULL field data type is date/time

CodePudding user response:

CodePudding user response:

In the "browse" window to open the table,
In this table, we want to record the fields to insert cursor, and press CTRL + 0 (zero),

CodePudding user response:

To allow NULL values in field
Open the table in table designer,
In the fields TAB, click the field of NULL columns,
When the field allows NULL values, the field of NULL columns show the check mark, to stop allows NULL values in the field, click the button to check mark at the NULL columns are cleared,

CodePudding user response:

To programmatically allows NULL values in field
When creating a TABLE, use contain NULL or NOT NULL clause of the CREATE TABLE SQL command,
- or -
To edit an existing TABLE, USE the USE command to open the TABLE and then USE a NULL or NOT NULL clause of the SQL ALTER TABLE command,

CodePudding user response:

Table in the database (DBC) (DBF) is allowed by the NULL, free table (DBF) value cannot be NULL

CodePudding user response:

Suggest using character storage date field

CodePudding user response:

refer to the 6th floor ten beans three response:

advice with character storage date field

Teacher, can you help me to solve my problem, but I released post, ask here!

I compiled DLL, can use in VFP environment, but from VFP after prompt "can't find the DLL class definition"
One, the development environment: Windows 7 environment programming, VFP version is sp2.
Second, running environment: msvcr71. DLL, vfp9r. DLL, vfp9rchs. DLL, vfp9t. DLL, GdiPlus. DLL has released along with
Three, test environment: Windows 7, Windows xp, a total of 5 computers
Four, the testing process:
1. Windows 7 can run directly within the development environment,
2. The same Windows 7 computer VFP environment with runtime, need to manually register to run, write the bat file can run normal registration,
3. In other computers, xp environment, the installation of VFP by CMD registered success,
4. Xp environment, never install the VFP repeatedly prompt registration is not successful,
5. The computer system is different, but prompt error registration is not successful!
6. Online solutions basic tried!

Five, tip error: "can't find the DLL class definition,"

Part six, the code:
1. CLASS defined in the DLL: DEFINE the CLASS MainDll AS Session OLEPUBLIC
2. EXE call DLL:
SFilePath='mydll. DLL'
The RUN/n regsvr32/s (sFilePath) & amp; & Here is registered, but not success!
3. CMD manually register code: regsvr32 mydll. DLL
4. Bat batch registration code: regsvr32 % ~ dp0mydll. The DLL
5. Simple example code mydll:
DEFINE a CLASS MainDll AS Session OLEPUBLIC

*! * just do a simple example to illustrate the issues related to

PROCEDURE shili
LPARAMETERS sOriginalValue, nFlag

DO case
CASE nFlag==1
? 'simple example 1:' sOriginalValue
CASE nFlag==2
? 'simple example 2:' sOriginalValue
ENDCASE

ENDPROC

*! * there are calls itself MainDll command, but should not omit this question also do!

ENDDEFINE

6. Attached above even the DLL, uploaded,
Mydll1. DLL: is a single-threaded even compiled
Multithreaded even compiled mydll2. DLL:
Click to download the DLL


Seven, the error message below:



Eight, the paranormal:
1. Start cannot register computer can register DLL, (try the way is more, how successful I also receive!) ,
2. If the installation directory is "ABC ", changed the installation directory name to "abcd ", that is, change the installation directory name, and then right-click the DLL is registered, or can be registered, but after running EXE, but can not find the control objects in the DLL, (note: the DLL files in the installation directory!)
3. Even after the registration registration again also not line!

Nine, solution

Thank you very much!