Introduction to access common fields

The following is a description of common fields in the access database:

BINARY - each character occupies 1 byte. Any type of data can be stored in this type in the field. No data conversion (for example, to text) is performed. How data is input into a binary field is displayed as output

BIT - 1 byte with values ​​of Yes and No, and the field can only take one of these two values.

TINYINT - 1 byte integer value between 0 and 255.

MONEY - 8 bytes Adjustable integer between –922,337,203,685,477.5808 and 922,337,203,685,477.5807.

DATETIME (see DOUBLE) – 8 bytes A date or time value between the years 100 and 9999.

UNIQUEIDENTIFIER - 128 bits A unique identification number used for remote procedure calls.

REAL —— 4 bytes single-precision floating point value, negative values ​​from – 3.402823E38 to – 1.401298E-45, positive values ​​from 1.401298E-45 to 3.402823E38, and zero.

FLOAT - 8 bytes double precision floating point value, negative values ​​from - 1.79769313486232E308 to - 4.94065645841247E-324, positive values ​​from 4.94065645841247E-324 to 1.79769313486232E308, and zero .

SMALLINT - 2 bytes short integer between – 32,768 and 32,767.

INTEGER - 4 bytes long integer between – 2,147,483,648 and 2,147,483,647.

DECIMAL - 17 bytes Exact numeric data type, ranging from 1028 - 1 to - 1028 - 1. You can define the precision (1 - 28) and size (0 -- defines the precision). The default precision and size are 18 and 0 respectively.

TEXT — 2 bytes per character (see Note) Zero to maximum 2.14 gigabytes (GB).

IMAGE - as needed from zero to a maximum of 2.14 gigabytes. Used for OLE objects.

CHARACTER——Each character occupies 2 bytes (see "Note") From zero to 255 characters

In the Java programming language, how to create Access fields.

　●BINARY (binary type): If you manually create table fields in Access, you cannot find this type. There are two keywords for creating this data field using Java language programming: BINARY and VARBINARY. You can choose any one.

　●BIT (yes/no type): There are 4 keywords to use Java language programming to create this data field: BIT, LOGICAL, LOGICAL1, YESNO, you can choose any one.

　●TINYINT (number, byte type): There are two programming keywords: INTEGER1, BYTE, you can choose any one.

　●MONEY (currency type): There are two programming keywords: MONEY and CURRENCY. You can choose any one.

　●DATETIME (date/time type): There are 4 programming keywords: DATETIME, DATE, TIME, TIMESTAMP, you can choose any one.

　●UNIQUEIDENTIFIER (numeric synchronous copy ID type): There is 1 programming keyword: GUID.

　●REAL (numeric single precision type): There are 4 programming keywords: REAL, SINGLE, FLOAT4, IEEESINGLE, you can choose any one.

　●FLOAT (numeric double precision type): There are 6 programming keywords: NUMERIC, FLOAT, DOUBLE, FLOAT8, IEEEDOUBLE, NUMBER. You can choose any one.

SMALLINT (numeric integer type): There are three programming keywords: SMALLINT, SHORT, INTEGER2, you can choose any one.

　●INTEGER (numeric long integer type): There are 4 programming keywords: INTEGER, LONG, INT, INTEGER4, you can choose any one. Note that Access's long integer is 4 bytes, not 8 bytes.

DECIMAL (decimal) In the Access Help "Equivalent ANSI SQL Data Types", the synonymous keyword for defining DECIMAL is NUMERIC, but when using NUMERIC, the field type is double precision. .

●TEXT (remarks) There are 4 programming keywords: LONGTEXT, LONGCHAR, MEMO, NOTE, you can choose any one.

●IMAGE (OLE object) There are 4 programming keywords: IMAGE, GENERAL, LONGBINARY, OLEOBJECT, you can choose any one.

●CHARACTER (text) Programming keywords are: TEXT(n), CHAR(n), ALPHANUMERIC(n), STRING(n), VARCHAR(n), you can choose any one. Note that (1) n cannot be greater than 255; (2) When only the TEXT keyword is used, the default size is 255.

●Automatic numbering: There are two programming keywords: COUNTER and AUTOINCREMENT, you can choose any one.

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