Inline BLOB / BINARY data types in SQL / JDBC

问题

Let's say I want to avoid using bind variables in JDBC and run SQL using "ad-hoc" statements, e.g:

connection.createStatement().executeQuery("SELECT ...");

Is there any convention / JDBC escape syntax to inline BLOB data types? I know that H2 has this syntax:

INSERT INTO lob_table VALUES (X'01FF');

But that's not a standard. Any general solutions? Note, I'm interested in a general approach. I know that this can turn out to be terribly inefficient.

回答1:

There probably isn't a JDBC escape syntax, so I searched around a bit and found and successfully tested the following:

SQL Server, Sybase ASE, Sybase SQL Anywhere
```
INSERT INTO lob_table VALUES (0x01FF);
```

DB2

-- Use a blob constructor. This is not needed for VARCHAR FOR BIT DATA types
INSERT INTO lob_table VALUES (blob(X'01FF'));

Derby, H2, HSQLDB, Ingres, MySQL, SQLite

INSERT INTO lob_table VALUES (X'01FF');

Oracle

-- As mentioned by a_horse_with_no_name, keep in mind the relatively low
-- limitation of Oracle's VARCHAR types to hold only 4000 bytes!
INSERT INTO lob_table VALUES (hextoraw('01FF'));

Postgres

-- There is also hex encoding as of Postgres 9.0
-- The explicit cast is important, though
INSERT INTO lob_table VALUES (E'\\001\\377'::bytea);

See A.H.'s answer for more details about Postgres' hex encoding

SQL Standard

-- SQL actually defines binary literals as such 
-- (as implemented by DB2, Derby, H2, HSQLDB, Ingres, MySQL, SQLite):
<binary string literal> ::=
  X <quote> [ <space>... ] 
  [ { <hexit> [ <space>... ] <hexit> [ <space>... ] }... ] <quote>

<hexit> ::=
  <digit> | A | B | C | D | E | F | a | b | c | d | e | f

回答2:

I'd like to add some PostgreSQL specific stuff to Lukas' answer:

The shortest and most easiest solution would be (since PostgreSQL 9.0 at least):

insert into lob_table (data) values( E'\\x0102030405FF' )

without any cast (if the column is already a bytea one) and only one \\x mark right at the beginning. This is the "hex format" documented in the section Binary Data Types.

Regarding the X'01FF' syntax: According to the string constant documentation PostgreSQL does support it - for bit strings. And it seems, that there is no standard conversion from bit to bytea.

回答3:

public String binaryLiteral(Connection con, byte[] bytes) {
    String databaseName = con.getMetaData().getDatabaseProductName();
    String binary = DatatypeConverter.printHexBinary(bytes);
    switch(databaseName) {
        case "Microsoft SQL Server":
        case "ASE": // Sybase
        case "Adaptive Server Enterprise": // Sybase
            return "CONVERT(VARBINARY(MAX), '0x" + binary + "', 1)";
        case "Oracle":
            return "HEXTORAW('" + binary + "')";
        case "PostgreSQL":
            return "E'\\\\x" + binary + "'";
        case "DB2":
            return "blob(X'" + binary + "')";
        default:
            // SQL Standard (Derby, H2, HSQLDB, Ingres, MySQL, SQLite)
            return "X'" + binary + "'";
    }
}

来源：https://stackoverflow.com/questions/9320200/inline-blob-binary-data-types-in-sql-jdbc

标签

sql

jdbc

binary

blob

inline