Im trying to get this query to work but i get this error:
Unknown column 'zips.city' in 'having clause'
`$query = "SELECT
zips.*
FROM
zips
HAVING
zips.city LIKE '%$city%'
AND
zips.stateabbr LIKE '%$state%'
LIMIT 1";
$result = mysql_query($query) or die (mysql_error());`
my zips table has a city column, so im not sure what the problem is, i know im accessing the database because i can run this query with no errors:
$zip1query = "SELECT
zips.*
FROM
zips
WHERE
zips.zip = '$zip'
";
any advice would be much appreciated! thanks!
The having clause doesn't mean the same thing as the where clause : when running a simple query, you should use where -- which is what you did in your second query, that works.
having is used when the condition has to be applied on the result of a group by clause.
Which means that, here, your query should be build this way :
$query = "SELECT zips.*
FROM zips
where zips.city LIKE '%$city%'
AND zips.stateabbr LIKE '%$state%'
LIMIT 1";
With that, if you still have an error about a non-existing or not-found column (at least for city and/or stateabbr), it'll be because that column doesn't exist in your table.
In this case, there is not much we can do : you'll have to check the structure of your table, to determine which columns it contains.
You can check that structure using a web-based tool like phpMyAdmin, or using an SQL instruction such as :
desc zips;
For reference, quoting MySQL's manual page for select :
The SQL standard requires that HAVING
must reference only columns in the
GROUP BY clause or columns used in
aggregate functions. ...
Do not use HAVING for items that
should be in the WHERE clause.
For example, do not write the
following:
SELECT col_name FROM tbl_name HAVING col_name > 0;
Write this instead:
SELECT col_name FROM tbl_name WHERE col_name > 0;
...
The HAVING clause can refer to
aggregate functions, which the WHERE
clause cannot
Try using WHERE instead of HAVING.
The proper way to do it is by using a WHERE clause.
$query = "SELECT
zips.*
FROM
zips
WHERE
zips.city LIKE '%$city%'
AND
zips.stateabbr LIKE '%$state%'
LIMIT 1";
HAVING is to be used when you are GROUPing, see here for an explanation
o jeez sorry guys i figured out the problem, apparently i put a space before city when i named the columns in my table. so i renamed the column and it works thanks anyway chaps! but using the where function instead of having must speed things up alot, thanks guys!
Related
im making a simple admin module to query the database to show the results. Im using this query via php:
SELECT
*
FROM myTable
WHERE id in(SELECT
id_registro
FROM myOtherTable
where id_forma='".$id_club."' and fecha_visita Like '%".$hoy."%'
)
order by id DESC
The result shows, however, it takes very long like 2 minutes..Anyone can help me out?
Thanks!
Without seeing your database, it is hard to find a way to make it faster.
Maybe you can try to turn your WHERE IN to INNER JOIN. To something like this
SELECT * FROM myTable INNER JOIN myOtherTable
ON (myTable.id = myOtherTable.id_registro)
WHERE myOtherTable.id_forma = '$id_club'
AND myOtherTable.fecha_visita LIKE '%$hoy%'
ORDER BY myTable.id DESC
Noted that you should sanitize your variable before putting it SQL query or using PDO prepare statement.
Sub Queries takes always time, so its better to ignore them as much as possible.
Try to optimize your query by checking its cardinality,possible keys getting implemented by DESC or EXPLAIN , and if necessary use FORCE INDEX over possible keys.
and I guess you can modify your query as:
SELECT
*
FROM myTable
inner join id_registro
on (id = id_forma )
where
id_forma='".$id_club."' and fecha_visita Like '%".$hoy."%'
order by id DESC
LIKE in mysql may take a long time ,with or without index.
Do u have a very large DB?
I need to find the largest value from one particular column in a mysql table where the value of another column is equivalent to something. But, with the query that I'm using, I keep on getting a message that displays and SQL error. My query is aS follows:
SELECT MAX(message_id) AS top_message HAVING(child_id) = '".$message_id[$i]."'
Any suggestions?
You are also missing a table name:
SELECT MAX(message_id) AS top_message FROM tablename WHERE child_id = '".$message_id[$i]."'
You should use WHERE instead of HAVING Clause:
SELECT MAX(message_id) AS top_message
FROM tablename
WHERE child_id = '".$message_id[$i]."'
Use only HAVING clause when you have an aggregated conditon.
You need a from clause and a where clause. The having clause is used for group filters. You don't have a group by clause, so there is no reason to write a having clause. If the table where you want to select from is called 'MyTable', then your query is as follows:
SELECT MAX(message_id) AS top_message
FROM MyTable
WHERE child_id = '".$message_id[$i]."'
Note, that the paranthesis around child_id is not needed. Please read SQL and MySQL tutorials for more information, your life will be much easier.
I want to do a SELECT on an empty table, but i still want to get a single record back with all the column names. I know there are other ways to get the column names from a table, but i want to know if it's possible with some sort of SELECT query.
I know this one works when i run it directly in MySQL:
SELECT * FROM cf_pagetree_elements WHERE 1=0;
But i'm using PHP + PDO (FETCH_CLASS). This just gives me an empty object back instead of an row with all the column names (with empty values). So for some reason that query doesn't work with PDO FETCH_CLASS.
$stmt = $this->db->prepare ( $sql );
$stmt->execute ( $bindings );
$result = $stmt->fetchAll ( \PDO::FETCH_CLASS, $class );
print_r($result); // Empty object... I need an object with column names
Anyone any idea if there's another method that i can try?
Adding on to what w00 answered, there's a solution that doesn't even need a dummy table
SELECT tbl.*
FROM (SELECT 1) AS ignore_me
LEFT JOIN your_table AS tbl
ON 1 = 1
LIMIT 1
In MySQL you can change WHERE 1 = 1 to just WHERE 1
To the other answers who posted about SHOW COLUMNS and the information scheme.
The OP clearly said: "I know there are other ways to get the column names from a table, but i want to know if it's possible with some sort of SELECT query."
Learn to read.
Anyway, to answer your question; No you can't. You cannot select a row from an empty table. Not even a row with empty values, from an empty table.
There is however a trick you can apply to do this.
Create an additional table called 'dummy' with just one column and one row in it:
Table: dummy
dummy_id: 1
That's all. Now you can do a select statement like this:
SELECT * FROM dummy LEFT OUTER JOIN your_table ON 1=1
This will always return one row. It does however contain the 'dummy_id' column too. You can however just ignore that ofcourse and do with the (empty) data what ever you like.
So again, this is just a trick to do it with a SELECT statement. There's no default way to get this done.
SHOW COLUMNS FROM cf_pagetree_elements;
This will give a result set explaining the table structure. You can quite easily parse the result with PHP.
Another method is to query the infomrmation schema table:
SELECT column_name FROM information_schema.columns WHERE table_name='cf_pagetree_elements';
Not really recommended though!
You could try:
SELECT * FROM information_schema.columns
WHERE table_name = "cf_pagetree_elements"
Not sure about your specific PHP+PDO approach (there may be complications), but that's the standard way to fetch column headings (field names).
this will list the columns of ANY query for PDO drivers that support getColumMeta. I am using this with SQL server and works fine even on very complex queries with aliased tables, sub-queries and unions. Gives me columns even when results are zero
<?php
// just an example of an empty query.
$query =$PDOdb->query("SELECT * from something where 1=0; ");
for ($i=0; $i<$query->columnCount(); $i++) {
echo $query->getColumnMeta($i)['name']."<br />";
}
?>
Even without PDO in the way, the database won't return the structure without at least one row. You could do this and ignore the data row:
SELECT * FROM cf_pagetree_elements LIMIT 1;
Or you could simply
DESC cf_pagetree_elements;
and deal with one row per field.
WHERE 1=0 does not work for me. It always returns empty set.
The latest PDO for SQLSVR definitely works with get column meta.
Simply set up your statement and use this to get an array of useful information:
$stmt->execute();
$meta= array();
foreach(range(0, $stmt->columnCount() - 1) as $column_index)
{
array_push($meta,$stmt->getColumnMeta($column_index));
}
Complete solution for Oracle or MySQL
for any or some columns (my goal is to get arbitrary columns exactly as they are in DB regardless of case)
for any table (w or w/o rows)
$qr = <<<SQL
SELECT $cols
FROM (SELECT NULL FROM DUAL)
LEFT JOIN $able t ON 1 = 0
SQL;
$columns = array_keys($con->query($qr)->fetchAll(PDO::FETCH_ASSOC)[0]);
if($cols === "*") {
array_shift($columns);
}
YOu could use MetaData with;
$cols = mysql_query("SHOW COLUMNS FROM $tableName", $conn);
I have no idea why this isn't working. I've taken code from a previous project that works fine. I just want to select specific columns. Here's what im trying...
$result = mysql_query("SELECT when, where, name FROM tablename ORDER BY count DESC LIMIT 0, 20");
//I dont really know how to debug php well, so this is all I have to go by to know if its not working.
if (!$result)
{
echo "<p>Page load has failed please try again</p>";
}
if I select all like this it works fine:
$result = mysql_query("SELECT * FROM tablename ORDER BY count DESC LIMIT 0, 20");
If im doing an insert, that doesn't work either...
$query = "INSERT INTO tablename (when, where, name) VALUES ('$when' , '$where' , '$name');";
mysql_query($query);
I'm sure the spelling is correct i've looked at it several times, and even if I put
echo $row["name"]; and the others ect while using the select all * they appear...
It just seems like its happening when im selecting individual columns.
I have other tables, with other sites using the same exact code and its working fine.
How can i fix this? or at least how can i debug the php to get some better error messages?
edit:
I'm sure the values going in are good, its just simple helloworld string
I've tried including count in the select incase that needed to be there for the sort, but that didnt make it work.
The word where is a reserved word (the WHERE clause of SELECT, UPDATE and DELETE queries). So is when. count is a built-in function name but can be used as an identifier, though you shouldn't.
If you use it as an identifier, you must always enclose it in `backticks` in the query. I recommend not using parts of the query language as column names.
http://dev.mysql.com/doc/refman/5.1/en/reserved-words.html
WHERE, WHEN and COUNT are reserved MySQL words (http://dev.mysql.com/doc/refman/5.1/en/reserved-words.html). Use backticks like this.
$result = mysql_query("SELECT `where`, `when`, name FROM tablename ORDER BY `count` DESC LIMIT 0, 20");
where is a reserved sql word, use tablename.where to select the correct column.
I was reading through our code base at my company and I saw something that seemed like it could be done better.
$dbRow = $dbh->Execute("SELECT * FROM database.table LIMIT 1");
$tableColumnCount = $dbRow->_numOfFields;
Is this the only way to get a column count using ADODB? It just seems silly to have to execute a query so you can ask the question.
You can use the INFORMATION_SCHEMA.COLUMNS table:
SELECT COUNT(*)
FROM INFORMATION_SCHEMA.COLUMNS
WHERE table_name = 'your_table_name'
AND table_schema = 'your_database_name'
That said, you might want to run the FLUSH TABLES command prior to for the INFORMATION_SCHEMA.COLUMNS to reflect existing tables and columns because the data is cached.
Whichever way, you'll have to end up hitting the database unless your program can magically know the schema of the table. If LIMIT 0 is legal in MySQL then this would be slightly more efficient - as I expect would replacing LIMIT 1 with WHERE 1 = 0.
MetaColumns or MetaColumnNames should give you this information