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Introduction to 1.Oracle data types

When you create a table, you must specify a data type for each column. The following are the categories of the Oracle data type:

two。 Character data type

The CHAR data type is used when a fixed-length string is required.

The CHAR data type stores alphanumeric values.

The column length of the CHAR data type can be 1 to 2000 bytes.

The VARCHAR2 data type supports variable length strings

The VARCHAR2 data type stores alphanumeric values

The size of the VARCHAR2 data type ranges from 1 to 4000 bytes

The LONG data type stores variable length character data

The LONG data type can store up to 2GB

3. Numeric data types can store integer, floating-point and real data with a precision of up to 38 bits

Declaration syntax for numeric data types:

NUMBER [(p [, s])]

P for precision and S for the number of decimal places

4. Date-time data type

Date-time data type stores date and time values, including year, month, day, hour, minute, second

DATE-stores the date and time parts, accurate to the entire second

TIMESTAMP-stores date, time, and time zone information with seconds accurate to 6 decimal places

5. Binary data

The RAW data type is used to store binary data

The RAW data type can store up to 2000 bytes

The LONG RAW data type is used to store variable length binary data

The LONG RAW data type can store up to 2 GB

6. Pseudo columns in Oracle are like a table column, but they are not stored in a table. Pseudo columns can be queried from the table, but their values cannot be inserted, updated, and deleted. The common pseudo columns are ROWID and ROWNUM.

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