Couldnt get records from mysql db - mysql

The below query is not updating records in mysql.
update audit_login set used_by=null where used_by = "test1\suri";
select is also not fetching the records, but mysql workbench shows 2 records when queried on a different column.
When the following is run:
SELECT * FROM audit_login WHERE used_by like 'test%\suri`;
I get records back with used_by of test1\suri.
Please help

The backslash (\) is used as an escape character. To use a literal backslash, you must escape it:
mysql> SELECT * FROM audit_login WHERE used_by = "test1\\suri";
+--------+------------+
| seq_no | used_by |
+--------+------------+
| 1234 | test1\suri |
+--------+------------+
1 row in set (0.00 sec)

Related

can a mysql select query in C language return a field with the special characters escaped?

1- string = a'b"c\d
2- escaped_string = a\'b\"c\\d
3- make an insert query that inserts escaped_string in some table field.
4- make a select query that returns the inserted value.
The returned value is: a'b"c\d
Is there a way to get the select query to return a\'b\"c\\d ?
(I understand that i can escape it again).
You can use the QUOTE() function of mysql:
mysql> select data from x;
+---------+
| data |
+---------+
| a'b"c\d |
+---------+
1 row in set (0.00 sec)
mysql> select quote(data) from x;
+-------------+
| quote(data) |
+-------------+
| 'a\'b"c\\d' |
+-------------+
1 row in set (0.00 sec)
This should exactly do what you are looking for. Note that the " doesn't need to be escaped here, so QUOTE() doesn't escape it, too.

Sorting order behaviour between Postgres and Mysql

I have faced some strange sort order behaviour between Postgres & mysql.
For example, i have created simple table with varchar column and inserted two records as below in both Postgres and Mysql.
create table mytable(name varchar(100));
insert into mytable values ('aaaa'), ('aa_a');
Now, i have executed simple select query with order by column.
Postgres sort order:
test=# select * from mytable order by (name) asc;
name
------
aa_a
aaaa
(2 rows)
Mysql sort order:
mysql> select * from mytable order by name asc;
+------+
| name |
+------+
| aaaa |
| aa_a |
+------+
2 rows in set (0.00 sec)
Postgres and mysql both returning same records with different order.
My question is which one correct?
How to get results in same order in both database?
Edited:
I tried with query with ORDER BY COLLATE, it solved my problem.
Tried like this
mysql> select * from t order by name COLLATE utf8_bin;
+------+
| name |
+------+
| aa_a |
| aaaa |
+------+
3 rows in set (0.00 sec)
Thanks.
There is no "correct" way to sort data.
You need to read up on "locales".
Different locales will provide (among other things) different sort orders. You might have a database using ISO-8859-1 or UTF-8 which can represent several different languages. Rules for sorting English will be different for those from French or German.
PostgreSQL uses the underlying operating-system's support for locales, and not all locales are available on all platforms. The alternative is to provide your own support, but then you can have incompatibilities within one machine.
I believe MySQL takes the second option, but I'm no expert on MySQL.

mysql strange behavior when inserting data

When inserting data to mysql via the phpmyadmin page, or via python I've seen something I can't explain:
cur.execute("INSERT INTO 28AA507A0500009E (timestamp, temp) VALUES ('2014-01-04 15:36:30',24.44)")
cur.execute("INSERT INTO 28D91F7A050000D9 (timestamp, temp) VALUES ('2014-01-04 15:36:30',24.44)")
cur.execute("INSERT INTO `28012E7A050000F5` (timestamp, temp) VALUES ('2014-01-04 15:36:30',24.44)")
Notice the last entry with the ` around the table name.
The first 2 entry's work fine without the apostrophe.
I can also put the apostrophes around all the table names and it still works.
Why can I remote the apostrophes from the first 2 lines, and not the 3rd one?
The tables are all created equally.
Edit 1:
In due respect to the following comments:
Your explanation is not entirely accurate. There is no alias in
the INSERT statement. I think that the part of the identifier after
28012E7 is just discarded as MySQL tries convert the identifier to
an integer value! – ypercube
these are table names not column names. – Sly Raskal
Well, MySQL sure have discarded the part of the table name identifier. My intention was to bring forward how a identifier name was interpreted when the system could not find it in the list of accessible table names ( I chose column/expression names in my examples ). As the engine interpreted it as a valid number but not as an identifier to represent a table, it threw an exception.
And I chose SELECT to clarify, why the table identifier was rejected for not putting in back quotes. Because it represents a number, it can't be used as an identifier directly, but should be surrounded with back quotes.
MySQL allows to suffix aliases just after numerics, numeric expressions surrounded by braces or literals. To one's surprise, a space between them is optional.
In your case, 28012E7A050000F5 is a valid exponent form ( 28012E7 ) of number 280120000000 suffixed with alias A050000F5. And hence 28012E7A050000F5 can't be used as a column name without back quotes. See following observations:
mysql> -- select 28012E7 as A050000F5;
mysql> select 28012E7A050000F5;
+--------------+
| A050000F5 |
+--------------+
| 280120000000 |
+--------------+
1 row in set (0.00 sec)
Following are some valid examples:
mysql> -- select ( item_count * price ) as v from orders;
mysql> select ( item_count * price )v from orders;
+-----+
| v |
+-----+
| 999 |
+-----+
1 rows in set (0.30 sec)
mysql> -- select ( 3 * 2 ) as a, 'Ravinder' as name;
mysql> select ( 3 * 2 )a, 'Ravinder'name;
+---+----------+
| a | name |
+---+----------+
| 6 | Ravinder |
+---+----------+
1 row in set (0.00 sec)

Mysql query with single quotation mark in the where clause

I have this query:
SELECT * FROM tbname WHERE LCASE(title) LIKE '%l\'infinito%'
The value into the table contains slash before quote.
Why the query returns no results?
thanks
The escaping is correct. You actually do not need LCASE since LIKE is not case sensitive (at least not on my Linux system):
mysql> SELECT 'L\'Infinito' LIKE '%l\'infinito%';
+------------------------------------+
| 'L\'Infinito' LIKE '%l\'infinito%' |
+------------------------------------+
| 1 |
+------------------------------------+
1 row in set (0.00 sec)
Maybe you want to search L'Infinito, with an 'n'. Or maybe the title seems to contain a single quote, but it is one of those never sufficiently damned Windows Word reverse English quotes.
Or maybe there is a space in the title after the quote. In many fonts, this is not immediately visible.
L' infinito
Can you search using '%ifinito%' (or '%infinito%'), and verify that the found row does indeed contain a single ASCII quote?
UPDATE
...and finally, maybe the database is wrong. To wit:
mysql> CREATE TABLE catalogo (title varchar (32));
mysql> INSERT INTO catalogo VALUES ('L\'Infinito');
mysql> SELECT * FROM catalogo;
+------------+
| title |
+------------+
| L'Infinito |
+------------+
If you run the same SELECT as before, does MySQL return L'Infinito without escaping? Because if you have instead
+-------------+
| title |
+-------------+
| L\'Infinito |
+-------------+
then the title has been saved wrong, escaping the quote sign TWICE. So there is an escape sign between the L and the quote, and you would have to search for
L\\\'Infinito
to "neutralize" the error.
Try this:
SELECT * FROM tbname WHERE LCASE(title) LIKE '%l\\\'infinito%'
The following query will answer your question:
string s="'infinito";
s=s.Replace("'", "''");
SELECT * FROM tbname WHERE LCASE(title) LIKE '%s%'

About mysql regex,how do I search and return string use mysql regex

My table filed's value is "<script type="text/javascript"src="http://localhost:8080/db/widget/10217EN/F"></script>",
I want to analyse this string and fetch the id 10217,how to do use mysql regex?
I know python regex group function can return the id 10217,but i'm not familiar with mysql regex.
Please help me,Thank you very much.
MySQL regular expressions do not support subpattern extraction. You will probably have better luck iterating over all of the rows in your database and storing the results in a new column.
As far as I know, you can't use MySQL's REGEXP for substring retrieval; it is designed for use in WHERE clauses and is limited to returning 0 or 1 to indicate failure or success at a match.
Since your pattern is pretty well defined, you can probably retrieve the id with a query that uses SUBSTR and LOCATE. It will be a bit of a mess since SUBSTR wants the start index and the length of the substring (it would be easier if it took the end index). Perhaps you could use TRIM to chop off the unwanted trailing part.
This query get the Id from the field
SELECT substring_index(SUBSTRING_INDEX(testvar,'/',-3),'EN',1) from testtab;
where as testtab - is table name , testvar - is field name
inner substring get string starts with last 3 / which is
mysql> SELECT SUBSTRING_INDEX(testvar,'/',-3) from testtab;
+----------------------------+
| SUBSTRING_INDEX(testvar,'/',-3) |
+----------------------------+
| 10217EN/F"> |
| 10222EN/F"> |
+----------------------------+
2 rows in set (0.00 sec)
outer substring get
mysql> SELECT substring_index(SUBSTRING_INDEX(testvar,'/',-3),'EN',1) from testtab;
+----------------------------------------------------+
| substring_index(SUBSTRING_INDEX(testvar,'/',-3),'EN',1) |
+----------------------------------------------------+
| 10217 |
| 10222 |
+----------------------------------------------------+
2 rows in set (0.00 sec)