concat to text field - mysql

I have a table with 1 column "textField". Our version of mysql won't allow for full text fields to have a default value, the default is null.
When we want to update our table we want to append a value to whatever is in textField, like so:
update table set textField = concat( textField ,'value')...this works when there is something already in the field, but won't work if the field is null. Since mysql won't allow for a default value in a full text field the above statement won't work.
A solution is to do 2 queries:
1. check if that field is null
2. if so, then don't do a concat & just update w/ the value...if not null then do the concat
We'd rather not do 2 queries if we can avoid it...is there a one-liner alternative that would work?


Try this:
update table set textField = concat(COALESCE(textField, '') ,'value')...


concat(ifnull(textfield, ''), 'value')

Related

SQL, Edit a field in a table row, entering a character at the beginning and at the end.

I need, through an SQL query, to wrap the field in a table row as follows:
field: my-long-text
field after update: [:en]my-long-text[:]
how can I move?

An UPDATE query and a CONCAT should be enough:
update tablename
set
field = concat('[:en]', field, '[:]')
If field is null concat will return null, but you can exclude with where field is not null and of course if the field is already wrapped you have to exclude it somehow (but this depends on your logic).

Trying to use update query to only update fields that are blank in Microsoft Access

I am trying to use an update query to update fields from one table to another for fields but only if the fields in the table that i am updating into is blank. If they contain information, I do not want to overwrite the existing data
e.g
Field: Name
Table: Table 1
Update to: [Table2.][Name]
Criteria:
I am unsure of what to put in the criteria. I tried, 'Is Null', Like "".

Here is an example:
UPDATE MyTable SET MyTable.FieldB = "MyNewValue" WHERE (((MyTable.FieldB) Is Null));

Looking at the Query from within Access, you can switch to SQL view. You just need to put Is Null in the criteria column: UPDATE MyTable SET MyTable.FieldB = "MyNewValue" WHERE (((MyTable.FieldB) Is Null));
Furthermore, you can just write Is Null on alternate lines and it will count as OR.

MYSQL: Update field with concat of multiple fields

I'm trying to update a field of my table with the CONCAT of the some fields of the same table.
Whith this
UPDATE tabex SET field1=CONCAT(tabex.a1,', ',tabex.a2,', ',tabex.a3,', ',tabex.a4,', ',tabex.a5,', ',tabex.a6,', 'tabex.a7,', ',tabex.a8,', ',tabex.a9 );
This query has 0 rows affected and no errors.
With this other query
UPDATE tabex SET field1=CONCAT_WS(tabex.a1,', ',tabex.a2,', ',tabex.a3,', ',tabex.a4,', ',tabex.a5,', ',tabex.a6,', 'tabex.a7,', ',tabex.a8,', ',tabex.a9 );
If the content of some of a(n) fields is NULL mysql puts a copy of the previous result
Someone can help me?

When this query
UPDATE tabex SET field1=CONCAT(tabex.a1,', ',tabex.a2,', ',tabex.a3,', ',tabex.a4,', ',tabex.a5,', ',tabex.a6,', 'tabex.a7,', ',tabex.a8,', ',tabex.a9 );
doesn't affect a row, the only explanation would be, that the table is empty. It would update every row in the table. But if one of the columns is NULL, your field1 column will also be NULL.
To avoid that, you have to use the COALESCE() function. This function returns the first of its parameters which is not NULL.
UPDATE tabex SET field1=CONCAT(COALESCE(tabex.a1, ''),', ',...);
On a sidenote I have to ask, why you want to do this. Comma separated values in columns are a bad idea most of the times.
And finally, your query using CONCAT_WS() is wrong. The _WS in the function name is short for "with separator", so the first parameter is the separator which then is placed between the other parameters of the function. So you should write it like this:
UPDATE tabex SET field1=CONCAT_WS(',', tabex.a1, tabex.a2, tabex.a3,...);
Another advantage of the CONCAT_WS() function is, that it ignores NULL values. Read more about the two functions in the manual.

Adding text to each column of MYSQL Database

I have a database table in MYSQL with around 1000 rows. In the table I have a column called 'overview'. In each row, this column has some value and at the end of that value I have a specific line (text) starting with: 'Source...'
Now what I want is, I want to remove this line from each column and replace it with some other text content.
I believe it can be accomplished with some smart query.

You can simply use REPLACE in your query like this
UPDATE your_table SET col_name = REPLACE(col_name , ‘Source...’, ‘new_val’)
WHERE col_name LIKE '%Source...';
Check Out the SQLFIDDLE.

MySQL database has a handy and simple string function REPLACE() that allows table data with the matching string (from_string) to be replaced by new string (to_string).
The syntax of REPLACE is:
REPLACE (text_string, from_string, to_string)
In your case, you can do this way:
UPDATE `tableName` SET `column` = REPLACE(column , 'Source...', 'Replaced Value')

Use Replace
update TBL
set overview = Replace(picture, 'Source..', 'replacement')
keep a backup of the table before anything.Or you can do it on a copy.

you can do this by following:
update table_name set col_name = replace(column_name , ‘Source...’, ‘Replaced String...’);

How do I replace all my NULL values in a particular field in a particular table?

I've looked all over the internet for my answer, and perhaps I'm just doing things wrong. I have a column in my MySQL table that I need to replace all the NULL values with a text string in my SQL Query using phpMyAdmin. I don't want the output to come out that way, I want to actually replace the null values with the text string.
I've tried
UPDATE `tablename` SET fieldname = replace (fieldname, "", "textstring")
I've read up on
SELECT ISNULL(field,"replacetext)
But this only shows the output, but doesn't actually replace it in the table.
I can't figure this out, and I've wasted so much time trying to find an answer.

update tablename set fieldname = "textstring" where fieldname is null;

Have you tried
UPDATE `tablename` SET fieldname = '' where fieldname is null