How to convert CLOB type

In Oracle database, CLOB refers to a large character object that can be used to store a large amount of text data, but sometimes we need to convert CLOB type data into other formats to meet business needs. This article will introduce how to convert CLOB type.

CLOB type storage

The CLOB type is a more powerful and flexible data type than the VARCHAR2 and CHAR types. It can store text data up to 4 GB. In Oracle, CLOB type data is stored in the LOB segment behind the ROWID of the table in an implicit LOB manner. Therefore, when performing CLOB type operations, it needs to be accessed through the LOB function.

CLOB type conversion

Oracle provides the following functions to convert CLOB type data:

1. TO_CHAR

TO_CHAR function CLOB type data can be converted into a VARCHAR2 type string, but since the length of the VARCHAR2 type is limited, when the length of the CLOB type data exceeds the maximum length of the VARCHAR2 type, the data will be automatically truncated.

For example, the following statement can convert a CLOB type data into a VARCHAR2 type string:

SELECT TO_CHAR(clob_column) FROM table_name;

2. TO_NCLOB

TO_NCLOB function can Convert CLOB type data into NCLOB type data. NCLOB is a LOB type that can store Unicode characters in different countries or languages.

For example, the following statement can convert a CLOB type data into an NCLOB type data:

SELECT TO_NCLOB(clob_column) FROM table_name;

3. TO_BLOB

TO_BLOB function can convert CLOB type data is converted into a BLOB type data. BLOB is a LOB type that can store binary data.

For example, the following statement can convert a CLOB type data into a BLOB type data:

SELECT TO_BLOB(clob_column) FROM table_name;

4. TO_CLOB

TO_CLOB function can convert Convert a VARCHAR2 or CHAR type string into a CLOB type data.

For example, the following statement can convert a VARCHAR2 type string into a CLOB type data:

SELECT TO_CLOB('hello world') FROM table_name;

5. TO_NCLOB

TO_NCLOB function can Convert a VARCHAR2 or CHAR type string into an NCLOB type data.

For example, the following statement can convert a VARCHAR2 type string into an NCLOB type data:

SELECT TO_NCLOB('hello world') FROM table_name;

Summary

The CLOB type is a very powerful and flexible Data type. In Oracle database, we often need to convert CLOB type data into other types of data to meet business needs. This article introduces several CLOB type conversion functions in Oracle. Readers can choose the appropriate method for conversion according to their own needs.

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