Access Expression Builder

"+", "-", "*", "/" these symbols on behalf of the mathematical operation of the "plus", "minus", "multiply", "except" four of the operational symbols. Use the & symbol to force two expressions to join together, for example: the database & Use guide will return: The Database Usage guide, which is to concatenate the two strings together, the left string in front and the right string behind. As shown in the following figure.

"=", ">", "The four symbols, <, <>, respectively, are equal to, greater than, less than, and not equal to, and are used to determine whether a condition is satisfied, for example:" = 34 "means that a value equal to 34 o'clock does not satisfy this condition. "<> Beijing" means that when a value is not equal to the string "Beijing", the condition is satisfied.

The three logical operators of "and", "or" and "not" are used to connect these conditional expressions above. For example, ">100 and <300" means that the condition is satisfied only if a value is greater than 100 and less than 300, and ">100 or <300" means that the value is greater than 100 or less than 300, in fact, any number satisfies the condition; >100 "This expression means that if the value is not greater than 100, this condition is satisfied.

There is also a "like", this symbol and how to use it? This symbol is often used to logically determine the value of a character that satisfies a format type. So usually "like" is not used alone, often with some other symbols: "?" Represents any single character; "*" means 0 or more characters; "#" represents any number; "[Character list]" represents any single character in a list of characters; "[!??????]" means any single character that is not in the list of characters. Let's look at a few examples, like "China?" the Strings "Chinese" and "Chinese characters" all meet this condition; like "China *" the string "China", "Chinese", "PBC" all satisfy this condition; like "Table #" the string "Table 1", "Table 2" all satisfy this condition; like "[Beijing, Shanghai, Guangzhou]" only Strings "Beijing", "Shanghai", "Guangzhou" can meet the conditions; like "[!] Beijing, Shanghai, Guangzhou]" then only the string "Beijing", "Shanghai", "Guangzhou" can not meet the conditions.

ASC (string expression)

Represents the character code for the first letter in the string, returning an Integer. But this string expression cannot be without, or there will be an error.

For example, ASC ("a") returns to the 65 ASC ("a") to return the ("Apple").

CHR (character code)

Use the CHR function to return the character that is represented by the specified. The number from 0 to 31 is the same as the standard nonprinting ASCII code. The normal range of character codes is 0–255. The ChrB function acts on the byte data contained in a String. ChrB always returns a single byte instead of returning a character, one character may be one or two bytes. The ChrW function returns a String containing Unicode, which is functionally the same as the CHR function on a platform that does not support Unicode.

Example: CHR (65) returns a CHR (97) returns a.

DAVG (Numeric data field, table, or query)

can be used to calculate the average of a set of numbers in a particular recordset (a domain);

For example, the DAVG (product unit price, product information table) returns the average of the product unit price in the Product information table.

DCount (numeric data fields, tables, or queries)

Can be used to determine the number of records in a particular recordset (a field);

For example: DCount (product unit price, product information table) returns the number of records in product unit price in the Product information table.

DLookup (numeric data fields, tables, or queries)

Used to get the value of a particular field from a specified recordset (a domain);

For example: DLookup (product price, product information table) returns the value in the product price list in the Product information table.

DMin (numeric data fields, tables or queries); DMax (numeric data fields, tables, or queries);

The DMin and DMAX functions are used to determine the minimum and maximum values in a specified set of records (a domain);

For example: DMin (product unit price, product information table) returns the minimum value in the Product price list in the Product information table.

DSum (numeric data fields, tables, or queries)

Used to calculate the sum of a set of values in the specified recordset (a domain);

For example: DMin (product price, product information table) return to the "product price" in the "products" in the and.

DVar (numeric data fields, tables, or queries) DVarP (numeric data fields, tables, or queries)

Used to estimate the variance of a set of values in a particular set of records (a domain), DVarP to compute the variance of the population, and the DVar function to compute the variance of the population sample; If fewer than two records are referenced, the DVar and DVarP functions return NULL, indicating that the variance cannot be computed.