Access to binary data in MySQL

Today, I read MySQL documents and some online articles and learned how to process binary data in MySQL. Many examples are used to access image data, however, what I want to access is not image data, but it does not matter. It is binary data and there is no difference. I will summarize how to use C to access binary data in Linux. To insert binary data, follow these steps: 1. Define a buffer char Buf [Eb] (what EB? Enought big, hehe ~~~) 2. Fill in the standard SQL statement with functions such as sprintf or strcpy until the binary is inserted. Insert the binary in the following step. 3. Read Binary data to tmpbuf [size] in some way; For example, if you want to insert image file data, use fread (tmpbuf, 1, sizeof (tmpbuf), filestream), and then use The mysql_real_escape_string () function continues to fill the Buf (note that the end character ''' of the string to be entered in step 1 should be entered, that is, no ''''), this function is prototype: Unsigned long mysql_real_escape_string (MySQL * MySQL, char * To, const char * From, unsigned long length) The MySQL pointer is valid and a successfully connected handle. In other words, MySQL must be the handle returned by successfully executing the mysql_real_connect () function. If you see a function like mysql_escape_string, do not use it. It is almost abolished. 4. If you still have data to insert, continue step 2 and 3. 5. Add the remaining SQL language to form the complete SQL language. 6. You can use mysql_real_query () to execute the SQL language. Its prototype is as follows: Int mysql_real_query (MySQL * MySQL, const char * query, unsigned long length) Note: There is one important point to note, because binary data contains many characters such as 0 and so on, which may be interpreted as other meanings in the string, so we use the above mysql_real_escape_string () function to copy data, so we must have a variable to record the start and end positions of the query string Buf [Eb] so that we can know how long the query string is, at last, pass the length to the last parameter of the mysql_real_query function. If it is to query binary data, it is also very easy, I just want to say a few points: 1. Construct a query string. 2. Execute mysql_real_query query. 3. Use mysql_store_result to store the result. 4. Use mysql_fetch_row to retrieve a record for processing. To determine the length of binary data, use the mysql_fetch_lengths function to obtain the length.