Kneeling: Common Commands of VF6.0

Common commands and main program commands of VF6.0

First, the main command:

Second, common functions

Third, the main program statements

First, the main command:

1, create

Function: Create a new table.

Format: Create [|? Note that the command characters can take the first four characters, and then they can be omitted, that is, CREA.

, the same below; Parentheses indicate that parameters are optional; The pipe symbol indicates that only one of the two parameters can be selected and cannot be the same.

When to choose, the same below. )

Description: File refers to the file used to establish VFP database. Dbf extension, and add a question mark after the command, indicating that the system will

pop music

Dialog box asking the user to enter the name of the table to be created. If you don't add a file name or question mark to the command, a dialog box will pop up.

ask

Enter the name of the table you want to create.

2. Modify the structure

Function: Displays the file structure of the table and allows you to modify the structure of the table.

Format: modifying the structure

Note: The structure of the table file can only be displayed or modified after using the USE command to open the table file.

3. Add

Function: Append records at the end of the current table (whether there are records in the table or not) (in the current table, it refers to the table currently in use).

Format: Append [Blank]

Note: Adding a blank parameter after the APPEND command means adding a blank record at the end of the current table. No blank ginseng

When counting, it means adding a record at the end of the current table and asking the user to input the corresponding field content.

4. Insert

Function: Insert a new record in the middle of the table file.

Format: Insert [Before] [Blank]

Description: INSERT inserts a record after the current record;

INSERT BEFORE inserts a record before the current record;

Insert Before Blank Inserts an empty record before the current record.

5. browse

Function: It is mainly used to open the browsing window, consult the table file and make modifications at the same time.

Format: browse

6. Use

Function: Open and close table files.

Format: Use []

use

Description: The previous command is used to open the specified table file. If there are memo fields in the table, open the corresponding table at the same time.

about

Remarks file (. Fpt file); The latter command closes the currently open table file.

7. List and display

Function: Display the content, structure or status of the table. dbf)。

Format: list | display [off] [< [] [field] <; Expression table > [while <; Conditions >] [for <; situation

& gt]

[print | save to file < file >]

List | Show Structure to Print | To File < File >]

List | Display Status [Print | to File < File >]

Description: The command with OFF parameter indicates that the record number is not displayed, and the range specifies which records to operate, including:

record

What record number, the next n records from the current record, and all records from the rest of the current record to the end of the file.

Records, all

All the records. If no range is selected, the implied range is all; ; FIELDS are followed by field names separated by commas.

minute

Separated. WHILE is followed by conditions, and FOR is followed by conditions. The difference is that if the conditions after WHILE are met, the search will stop;

After ...

Standard Finds all records that meet the standard. TO PRINT and tofile respectively indicate that the results will be displayed on the printer.

dump

And output the display result to a file. The DISPLAY command requires the user to press any key to continue the display after the recording is displayed in full screen.

, and at

In this command, if the range is omitted, only the current record will be displayed. Format, the following two commands are to display the table structure (

Structure) and working STATUS.

8. Positioning of records

Function: Use the record pointer to locate the record.

Format: Go to record n | Top | Bottom

n

Skip [+|-]

Note: The first command is also called absolute positioning, where record n is positioned to record n and TOP is positioned to record 1.

BOTTOM locates the last record. The second command navigates to the nth record, where n is a numeric value. The third command is also called.

Relative determination

Bit, which moves N records forward (-) or backward (+) based on the current record. If this option is not selected, the record pointer will be returned by default.

Move the record.

9, modify and edit

Function: Display the fields to be edited or modified.

Format: change | edit [] [field < field name table >; ][WHILE & lt； Conditions >] [for <; Conditions >]

10, browse

Function: Opens the Browse window for users to browse or modify records.

Format: Browse [field; ]

1 1, replace

Function: Replace the contents of the corresponding field in the command with the value of the expression.

Format: replace [] < Field1>; Use< expression1>; [,< field 2 > Use < expression 2 >] [for <; deprive

Works >

][WHILE & lt； Conditions >]

12, delete, package, exchange and recall

Function: Mark the records to be deleted, delete all, delete all records, and cancel the selected table records.

about

Delete the flag.

Format: delete [] [while <; Conditions >] [for <; Condition >] (special case: delete file.

File name. DBF，

This command deletes the specified table file)

package

vitality

Memories [<; Scope >] [for <; Condition >] [while <; Conditions >]

13, sorting and indexing

Function: Create a new table file with records arranged in a new physical order, and represent the current table according to keywords.

The value of

Arranged from small TO large, stored in a file, and specified the index file name or the identifier of the composite index file after to.

Format: sort by ON< field name1> [/A] [/C] [/D][, < field name 2 > [a] [/c]

[/D]] ...

[ascending | descending] [<; Scope >] [for <; Condition >] [while <; Condition >] [field & lt field table >]

Index keyword expression on< > to< file name >

Index keyword expression on < > tag < distinguished name > [of < File name >] [for <; Conditions >]

Note: in the 1Command, /A sorts by field name in ascending order, /D sorts by field name in descending order, and/c ignores case and only pays attention to words.

Symbol type

For keywords, ascending and descending means ascending and descending respectively. Command 1 creates a. dbf table file, which is the first one.

2 commands

Create one. Idx single index file, and the third command creates a. cdx composite index file.

14, use < table file name > index < index file name list >; , set the index to and the order to.

Function: Open the index file, open the index file, and change the main index while opening the table file.

Format: use index < index file name list >;

Set the index to [<; Index file name list >; ]

Set the order to [<: Index file name >] (special case: REINDEX command: reindex)

15, search, search, locate, continue

Function: The first two commands, FIND and SEEK, locate the contents of keywords in the table where the index file has been established.

And fate

The first record in a row with the same string. After using USE to open the table file, the latter command directly queries the fields in the table.

Content.

Format: find |< string >

SEEK & lt emoticon >

Positioning [<: Scope >] [for <; Condition >] [while <; Conditions >]

continue

Note: The difference between the FIND command and the SEEK command is that the former is followed by a string, while the latter is followed by an expression. Use the positioning command.

find

After matching records, you can use the CONTINUE command to search the rest of the table to find other matching records.

16, counting

Function: Count the number of qualified records in the current table file.

Format: count [] [for <; Condition >] [while <; Condition >] [Recipient < memory variable name >; ]

Note: Memory variable names can be any characters except parameters.

17, total

Function: Accumulate all or specified numeric fields or numeric expressions composed of specified fields of the selected records in the current table.

And ...

Format: sum[][ numerical value] [to < Memory variable list >; ][FOR & lt； Condition >] [while <; Conditions >]

18, average

Function: display all or part of numeric fields and their expressions of the selected records in the current table on average.

Format: average[][ numerical value] [to < Memory variable list >; ][FOR & lt； Condition >] [while <; deprive

Piece > ]

Second, common functions

1, mathematical function

Functional usage

ABS(& lt； Numerical expression >) absolute value, |x|

Ceiling (< numerical expression >) > = the smallest integer of independent variable.

EXP(& lt； Numerical expression >) to the e power, e=2.7 1828.

Floor (< numerical expression >) < = the largest integer of the independent variable.

INT(& lt； Numeric expression >) rounding the independent variable.

Log (< numerical expression >) natural logarithm of independent variable, ln x

log 10(& lt； Numerical expression >) common logarithm of independent variable, LG X.

MAX(& lt； The expression1>; , < expression 2 >) the maximum value of two values.

MIN(& lt； The expression1>; , < expression 2 >) the minimum value of two values.

MOD(& lt； Numerical expression1>; , < numerical expression 2 >; ) find the remainder

Rand ([<; Numerical expression1>; ]) returns a pseudo-random number

Circle (< numerical expression1>; , < numerical expression 2 >; ) Rounds the first argument.

Sign (< numerical expression >) The sign of the independent variable.

SQRT(& lt； Numerical expression >) square root (positive root)

2. String operation function

Functional usage

& amp& lt memory variables >; Used to replace the contents of a memory variable.

LEN(& lt； String expression >) returns the number of characters in a string expression.

Space (< numerical expression >) generates spaces.

SUBSTR(& lt； String expression >,< numerical expression n>[,< numerical expression L>]) finds a substring from the specified word.

A string with a total length of l starting from the nth string expression.

Lower (< string expression >) converts string letters to lowercase letters.

UPPER(& lt； String expression >) converts string letters into uppercase letters.

TRIM(& lt； String expression >) removes trailing spaces from strings.

ASC(& lt； String expression >) returns the ASCII code of the leftmost first character of a string expression.

CHR(& lt； Numeric expression >) converts numeric expressions into characters.

In (< string expression1>; , < string expression 2 >; [,< numerical expression n<]) determines that the string expression 1 is in the character.

The position in string expression 2, where n is the number of occurrences of the string expression.

STR(& lt； Numeric expression > [,< Numeric expression L & gt][, < Numeric expression n>] converts a numeric value into a string, and l is a numeric value.

The total length of the expression, where n is the number of decimal places.

VAL(& lt； String expression >) converts a numeric string into a number.

Type (< expression >) detects the data type of the expression value.

LTRIM(& lt； String expression >) deletes the space to the left of the string.

RTRIM(& lt； String expression >) deletes the right space of the string.

Left (< string expression >, < numerical expression n<) takes the left part of the string, where n is the number of characters returned.

Right (< string expression >, < numerical expression n<) takes some characters on the right side of the string, and n intercepts the number of characters from the right side.

3. Table (. Dbf) operation function

Functional usage

BOF([& lt； Workspace code or alias >]) look-up table file startup function

EOF([& lt； Workspace code or alias >]) table file end test function

RECNO([& lt； Workspace code or alias >]) tests the current record number of the current or specified workspace table.

Deleted ([<; Workspace code or alias >]) Record deletion test function

File (< "string" >) tests the function of the file.

DBF([& lt； Workspace code or alias >]) Detection table of file name function

4. Date and time functions

Functional usage

DATE () queries the current date function of the system.

Time ([<; Numerical expression >]) Check the current time function of the system.

Year (< date expression > | < date time expression >; ) Appointment by Date function

Month (< date expression > | < date time expression >; ) check the month function from the date

CMONTH(& lt； Date expression > | < Date time expression >; ) Check the month name function by date.

Day (< date expression > | < date time expression >; ) Check the daily functions of the current month from the date.

Dow Chemical (< date expression > | < date time expression >; [,< numerical expression >]) The function of finding the day by date.

CDOW(& lt； Date expression > | < Date time expression >; ) find the day name function from the date.

DTOC(& lt； Date expression > | < Date time expression >; ) date to character function

CTOD(& lt； String expression >) string into the date function.

CTOT(& lt； String expression >) returns a date-time value function.

TTOC(& lt； Date time expression >; ) returns a character value.

5. Display and print position function

Functional usage

The ROW () function is used to determine the position of the line where the cursor is located.

COL () function for judging the position of cursor column.

Because of the base ([<; Numerical expression >]) detects the ASCII code function corresponding to the user's keystroke, and the numerical expression is in seconds.

be pressed for time

6. Other functions

Functional usage

DISKSPACE () is a function that returns the number of bytes available in the default disk drive.

OS () function to detect the operating system name.

VERSION () returns the VFP version number.

Third, the main program statements

1, conditional judgment statement

Format: (1) If

< command statement group >;

ENDIF

Description: If the condition is true, each statement in the command statement group will be executed; otherwise, these command statements will be skipped and not executed.

And execute the statement after ENDIF.

(2) if < condition >

& lt command statement group 1 >:

other

< command statement group 2 >:

ENDIF

Description: If the condition is true, the command statement group 1 is executed; otherwise, the command statement group 2 is executed.

(3) If < condition1>;

If < condition 2 >

& lt command statement group 1 >:

other

< command statement group 2 >:

ENDIF

...

other

& lt command statement group N>

ENDIF

Description: Nested selection for multiple conditions.

(4) Make a case

Case & lt condition1>;

& lt command statement group 1 >:

Case & lt condition 2>

< command statement group 2 >:

Case < condition 3 >

< command statement group 3 >:

...

...

Case & lt condition N>

& lt command statement group N>

[Otherwise]

[& lt； Command statement group n+ 1 >:]

Close the case

Description: judge the conditions in turn and switch to the execution of the command statement group with true conditions. When all the conditions are not true, if there is

Otherwise, execute the command statement group N+ 1, otherwise, execute the statement after ENDCASE.

2. Loop statement

Format: (1) do while

< command statement group >;

[circulation]

< command statement group >;

[exit]

< command statement group >;

Endor

Description: Judge whether the condition is true or not. If true, repeat the command statement group in the loop body until the condition is false, and end.

follow

The ring.

(2) scanning

< command statement group >;

End scan

Description: Establish a loop to execute the command statement groups in the table, and perform operations on each record until the table text.

piece

Until the record is over.

Description of common functions of using VFP

1, numerical operation function

Example result of function operation

Find the square root SQRT(9) 3

INT(x) takes the integer INT(3. 14) 3.

Circle (x) Circle (3.14159,4) 3.1416.

MOD(x, y) Find the remainder of x divided by y mod (25,4)1.

MAX(x, y) Find the maximum value of x, y Max (7,8) 8.

MIN(x, y) Find the minimum value of x and y MIN( 1, 2,3)1.

2. Character operation function

Example result of function name operation

Uppercase (s) lowercase letters uppercase (abc) ABC

Lowercase (s) uppercase letters lowercase (ACD) acd

Find the length of the string LEN ("China 1") 7.

In the AT(S 1, S2) of the string S2, look for the string S 1 AT("H ","China ") 2.

SUBSTR(S, i, n) gets n characters SUBSTR('TECHNOLO', 3,3 3) CHN from the i-th character in the S string.

LEFT(S, n) takes n characters from the left of the string S, LEFT ("China people ",4) China.

RIGHT(S, n) takes n characters from the right of the string S =' 12345'.

Right (South, 3) 345

SPACE(N) generates n spaces "total"+space (2)+"123", and the total is123.

TRIM(S) deletes the space at the end of the name of the string trim ("name").

ALLTRI(S) deletes all spaces in the string ALLTRIM ("Li Li") Li Li.

STUFF(S 1, N 1, N2, S2) replaces N2 character STUFF ("Now", 2,

1, "e") new

& replace P="G2 "with macro

Use & ampp Use G2

3, date and time function

Example result of function name operation

DATE () Find the current date () 20011112.

DATETIME () Find the current date and time Datetime () 20011112/0: 22: 33am.

YEAR(D) Find the year YEAR(DATE()) 200 1.

MONTH(D) Find the month (numerical value) Month (datetime ())11.

Find the month (character) month (date and time ()) 1 1 month.

Found the date DAY(DATE()) 12.

DOW(D) Find the day of the week (numerical value) DOW(DATE()) 1.

CDOW(D) Find the day of the week (English) CDOW(DATE ()) Sunday

TIME(D) Find the current time TIME(DATE()) 10:20:38am.

4. Data type conversion function

Example result of function name operation

ASC(S) Find the ASCII code ASC("what") 87 of the first string.

CHR(N) Find the character CHR(87) w of ASCII code.

The value of STR(R, l, d) is converted into characters, where l is the length and d is the decimal place X=3. 14 15.

STR(X，6，2) 3. 14

The VAL(S) string is converted into the numerical value VAL(" 123") 123.00.

CTOD(S) string CTOD ('11/01/2002')11/2002 so far.

DTOC(D) date is converted into string dtoc (date ())11/01/2002.

DTOS(D) converts the date into Japanese string dtos (date ()) 200211kloc-0/.

CTOT(C) string is converted to date and time ctot (11/200210: 30: 50am)11/065438+.

DTOT(D) date type is changed to date and time dtot (date ())1/25/200100: 001am.

TTOC(T) date-time type is changed to character type ttoc (datetime ())11/25/200100: 001am.

TTOD(T) date-time type is changed to ttod (datetime ())11/25/2001.

IIF(LE, E 1, E2) logic judgment IIF(A & gt；; 0, "Yes", "No") Yes

5. Detection function

Example result of function name operation

RECNO () detects the current record number RECNO() 1.

RECCOUNT () detects the current record count RECCOUNT() 12.

BOF () starts recording BOF() 1.

EOF () Last record EOF() 12

FOUND () returns the found search result (). T t。

ROW () returns the current row coordinate ROW() 1.

COL () returns the current column coordinate col 1.

SYS(N) returns the system status. SYS( 13) is online.

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