Mysql if null or empty stack overflow. Different meanings, you see.

Mysql if null or empty stack overflow Oct 3, 2016 · Just remove the group by. id > 10000; You seem to want the count of ids that meet the condition. 0. If it is empty or null I would want to use the already existing columns value or not changing it at all. 2. . Jun 30, 2018 · I see this is not answering original question of matching against empty array ([]) but this has worked for me, matching against empty dictionary ({}), at mysql 5. Aug 3, 2012 · Your code inside the while loop never runs if there are no results. It aids in keeping your data accurate and up-to-date, contributing to the overall health of your database. By default, when I add a new table row, the fk_ownerID is empty. It should fail on the insert - just like the int. Aug 21, 2010 · The following statement returns no rows, because expr = NULL is never true for any expression. In the same statement I would like to select as a result "content" if "intro" is empty, but not having both in the result array. file_last_known_location is not null and v. wp_second values should be only updated if null or empty. Example : I have table called "posts" which have "intro" and "content". ID OD CD 5 1213567200 // fine 6 1210629600 1281736799 // fine 7 1201042800 1248386399 // Should be empty 8 1205449200 1271282399 // fine I can't figure it out how to return empty/0/NULL if there is one (or more) empty colums for a client. Jan 18, 2013 · A table I need to run a query on has fields that can have a NULL value, an empty string, or some text, number, etc. I have read up on a few functions to do so, like COALESCE(EMAIL,"[email protected]"), but I am unsure on the placement of that function in the script. Since MySQL 5. Provide details and share your research! But avoid … Asking for help, clarification, or responding to other answers. If fk_ownerID is given a value, and I later remove this value, I set fk_ownerID = "". student_date is null then '01-01-2013' else sa. file_name is not null and v. An empty string is not NULL, so concat_ws would incorrectly include a delimitor ahead of empty strings. For any reason, MySQL (and MariaDB) are treating 0 values as it were empty strings or NULL values. To learn more, see our tips on writing great The picName can have a NULL value, a picture's name or it can be empty. Sep 8, 2018 · I found the solution. Thanks for any hint. Jun 7, 2016 · Thanks for contributing an answer to Stack Overflow! Please be sure to answer the question. !='', or <>'' as Ivan said in the accepted answer, will not return empty strings or NULL values. (This is true in MySQL and in many programming languages as well. idc = c. If it's a VARCHAR column (which it probably will be) then it's hardly taking much space anyway. So. Only update when value is not null mySQL. The syntax is as follows −. If you are concerned with performance, you'd need to read documentation of DBMS you are using and make some tests on your own. The query works fine however the issue I have is that on Duplicate key update, I only want to update wp_second table's those fields that have no values. My problem is I don't want to make many query for it for the filter condition, so my question is can I disregard a where condition if the value is null In DB I have a table with a field called fk_ownerID. Making statements based on opinion; back them up with references or personal experience. – Apr 24, 2012 · I wanted to skip blank data in MySQL. Edit 1: sorry i mistake with return field as null not result set,for result set return as null use Union and Exist Function like this: SELECT NULL AS Field1 FROM Table1 WHERE not EXISTS(SELECT Field1 FROM Table1 WHERE Field2>0) UNION SELECT Field1 FROM Table1 WHERE Field2>0 Apr 2, 2011 · Null and empty means NULL + '' (empty string)? select CASE WHEN description IS NULL or description = '' THEN 'null or empty' ELSE 'not null' END AS 'description' In your original query, there is no possibility of a third case because IS NULL and IS NOT NULL are complementary, between them they have covered all possibilities. May 7, 2025 · Thanks for contributing an answer to Stack Overflow! Please be sure to answer the question. For instance an employee needs to have a social security number but does not need to have a middle name. `current_date` ='23/1/2018' OR loading_buses. So it is a good practice to get use the Mar 5, 2013 · I've tried using both the Coalesce and IfNull functions, but nothing displays in my results, just an empty field under address2. SELECT COUNT(*) FROM table WHERE Context IS NULL OR Context = ''; So now I do not know where the problem is. I tried CONCAT and CONCAT_WS but it didn't work both of these didn't work: SELECT id, Apr 14, 2011 · Stack Overflow for Teams Where developers & technologists My belief is MySQL is similar, starting support in 4. mysql_fetch_array returns null/false if there are no more results. Very nice! – Sep 15, 2017 · Can someone indicate the proper syntax to determine whether a variable is NULL or empty and then take appropriate action to set the variable depending on the result. In other words IS NOT NULL is a subset of !='', but they are not equivalent. id WHERE deleted = 0 Sep 15, 2021 · Does anyone know how to check if a NodeJS MySQL result is null/empty? What I'm trying to do is (very succinctly explained) to check if result 5 is empty or not, and if it's not, then execute an action (console. Use the not null condition for columns that need to have a value by definition. I tried these commands separately. So, In this example we have created the Apr 14, 2016 · Let's say we have a Table in MySQL Database called TAB1 that Contains two Columns col1 : col2. The Answer above didn't work since the CLAUSE that was meant to filter out the NULL columns ran after the INNER JOIN was evaluated with the NULL or empty columns. May 29, 2021 · Stack Overflow for Teams Where developers & technologists share private knowledge with coworkers; Advertising Reach devs & technologists worldwide about your product, service or employer brand; Knowledge Solutions Data licensing offering for businesses to build and improve AI tools and models; Labs The future of collective knowledge sharing Dec 15, 2014 · Stack Overflow for Teams Where developers & technologists share private knowledge with coworkers; Advertising Reach devs & technologists worldwide about your product, service or employer brand Aug 22, 2014 · DELIMITER $$ CREATE PROCEDURE sp_empty() BEGIN SET @sql = NULL; SELECT GROUP_CONCAT( CONCAT('(SELECT GROUP_CONCAT(id) FROM Table1 WHERE `', column_name, '` IS NULL Oct 23, 2008 · Bill's answer is good, but a little bit outdated. Sep 21, 2020 · I'm making an API for our search with filter. The empty string specifically means that the value was set to be empty; null means that the value was not set, or was set to null. select count(t. Yes, what you are doing is correct. By passing an empty string as the second parameter, you are guaranteeing it will not return NULL. I have this: SELECT IFNULL(field1, 'empty') as field1 from tablename I need to add an additional check field1 != &quot;&quot; Feb 2, 2024 · Database Maintenance: Regularly checking for empty or null columns is part of routine database maintenance. Mar 18, 2014 · OP is asking about only rows that have something in the phone2 field. Nov 4, 2010 · Stack Overflow for Teams Where developers & technologists share private knowledge with coworkers; mySQL query for empty and NULL value together. What am I doing wrong? Feb 26, 2022 · The entire column appears empty - which it shouldn't be, because I already set the DEFAULT to be NULL. My sample query is: SELECT id, name, date from sample where name IS NOT NULL; Sample table: id name date 1 24-04-2012 2 ab Feb 15, 2022 · I would like to only update a column in a table if, the input value is not null or a empty string. the NULL vs. for sure @d will be filled from your form as parameter. Instead simply use party_zip IN ('49080', '49078', '49284'). Also tried with NULL fields. IS NOT NULL returns everything that literally is not set to NULL, even the empty string "". here is query I've so far Oct 3, 2012 · In SQL, null is very different from the empty string (""). This combination query of IS NULL keywords in the Select query extracts the subset rows having null or empty values in the column names. Coalesce will return the first non-null argument passed to it from left to right. So for instance I have a table "data" with fields id, field1, field2, field3, fi Apr 10, 2014 · Thanks for contributing an answer to Stack Overflow! mysql test IF variable IS NULL (or empty) 0. Also note that the COALESCE operator is supported in standard SQL. This query: Nov 14, 2013 · i have come up to this SELECT * FROM (select student_name, case when sa. Jun 8, 2019 · By using NULL you can distinguish between "put no data" and "put empty data". Jan 23, 2018 · if you want check for null you should use is null . SELECT IF(yourColumnName IS NULL or yourColumnName = '', 'NULLId', yourColumnName) as anyVariableName from yourTableName; Dec 15, 2015 · Is there a better way to do the following to check if a column is not empty/null? (v. Jun 10, 2015 · SELECT IF(col IS NULL OR col = '', 'empty', col) FROM tab With this query, you are checking at each dataset whether "col" is NULL or empty and depending on the result of this condition, either the string "empty" is returned in the case that the condition is TRUE or the content of the column is returned if not. Nov 24, 2012 · "This fields never contains null, empty title means no title", enforced with NOT NULL constraint on column) which is followed consistently you could take whichever approach you like. I think that for some reason it is not recognizing the field as null, but as having a space in them. NULL means the data is missing. This is a generic mysql query, where I would hope to only filter when the valueA or valueB (inclusive or) has a value that is not null, whitespace or empty string. Solution SELECT pid FROM planets WHERE userid IS NULL; To test for NULL, use the IS NULL and IS NOT NULL operators. Select userName from user where picName = '' Select userName from user where picName IS NULL But I want to get both the results in 1 query. What you need yo do is check with mysql_num_rows first, before the while. WHERE loading_buses. I cannot get this to work. `current_time` is null Or based on your comment you can use . That is, if you can't come up with a difference between the meaning of empty string and the meaning of null, then set the column up as NOT NULL and use empty string to represent empty. 22. Feb 5, 2013 · SELECT * FROM table WHERE id IN ('21') AND (content_id IS NULL OR content_id = 0 OR content_id = '') Is there a shorter way of writing this condition. Values in tbl1 should be updated/replaced with values from tbl2 in corresponding rows, if the values in tbl2 aren't NULL or empty strings (''). Is it possible to tell MySql something to the effect of: If address2 = " " then "none provided"? – Apr 4, 2013 · If you are explicitly setting the value to NULL in your insert, but want MySQL to replace the NULL with 0, one way to do that is to define the column to allow NULL in the CREATE TABLE statement, and then replace the NULL with a TRIGGER. 3 InnoDB uses COMPACT row format which uses only one bit to store a NULL (of course one byte is the minimum), therefore: Oct 13, 2011 · This solution is elegant. 1 - (Ubuntu). The values in this statement should return NULL (they don't exist in my database). 2015-06-12 at 18:11 Apr 25, 2021 · Checking for NULL values and handling them while displaying results is a key database operation. This is not the case of IFNULL. You are checking to make sure the email field is not an empty string. You can search for an empty string using a bound variable but not for a NULL. operator IS NOT NULL tests whether a value is not NULL. Jul 3, 2012 · Your best bet if you want a SQL only solution, is to create a regular index on the ISBN field, and then use a stored procedure to act as an insertion proxy--one that checks for uniqueness if not null or empty. Apr 1, 2013 · For those wonder, as I did, what the COALESCE function does: it returns the first non-NULL value parameter passed to it (or NULL if all parameters are NULL). Dec 30, 2015 · If you want the default value for your column to be NULL, then write DEFAULT NULL. Also, the ifnull() is unnecessary:. You can add the null check also. I want to query the userName of those entries whose picName is either NULL or empty. time_in END as time_in, case when sa. IFNULL(@previousTs, '2017-00-04 00:00:01') ts Oct 22, 2010 · Stack Overflow for Teams Where developers & technologists share private knowledge with coworkers Advertising Reach devs & technologists worldwide about your product, service or employer brand Knowledge Solutions Data licensing offering for businesses to build and improve AI tools and models May 18, 2016 · Iam struck up with a query. Example of Checking for Empty or Null Columns in MySQL Example 1: Checking for Null Values. student_date END as date from student_records sr left join student_attendance sa on sa Feb 22, 2012 · Stack Overflow for Teams Where developers & technologists share you have to remember to explicitly check for NULL or empty string: MySQL IF(NULL != "", 1, 0 Oct 11, 2010 · I know whats the difference between a NULL value and an empty string ("") value, but if I want to get a value by using the OR keyword, I get no result for a NULL value. AND (email != "" OR email IS NOT NULL) Stack Overflow for Teams Where developers I only want the UPDATE to execute if the $_POST value is not empty. It's all well and good saying that shorter code is better and we can rely on the "default default" to do this job for us, but the fact that every single existing answer on this question leaves you prone to a potentially catastrophic bug is proof of what a terrible approach that really is! Dec 14, 2021 · I'm trying to add link to my image when I return it from database but I don't want to add it when image is null. log in this case). id) as `count` from table t where t. 20-0ubuntu0. 04. operator IS NULL tests whether a value is NULL. While you can always add a WHERE clause to check for NULL in a column of a table, MySQL provides you with additional ways to tackle this problem. x. 0. In your given example, you don't need to include IS NOT NULL. the question is : is there a way to check is any of these Columns Contain a Null or Empty Value? for the Condition WHERE col_Name is null OR col_Name='', this Query checks one Column, I want to check all the Columns using a simple Query. 16. And for the empty check, simple matching of column name with blank character is checked. time_in is null then '' else sa. Something like this: Nov 23, 2016 · An empty string is different from null. `current_time` is null Nov 1, 2017 · insert into [table] (data) Values ((CASE WHEN @d IS NULL OR datalength(@d) = 0 THEN NULL ELSE @d END)) will check if the value is null or empty and if so, it will insert null otherwise it will insert the sent value. COUNT(message) will count empty strings but not NULLs. In Toad for MySQL, this is shown as {null}. time_out END as time_out, case when sa. This is the code without all the details, to simplify things, but when executing it I get that "result" is not defined May 6, 2013 · When comparing a NULL value, the result in most cases becomes NULL and therefor haves the same result as 0 (the FALSE value in MySQL) inside WHERE and HAVING. I have made this Query, but it seems a bit off as I am getting parse errors when executing the query. The MySQL ISNULL() function is used to check for any NULL values in the expression passed to it as a To check whether a field is null or empty in MySQL, use the IF() function in MySQL. I used JSON_OBJECT function but it is very likely the JSON_ARRAY will also work in similar way, creating the 'empty' object when called without arguments. According to this article, INNER JOIN won't work with fields that have NULL or empty values. Nov 1, 2021 · The same for say valueB if that were empty then no filtering would occur. How to deal with if subquery returns null in Having clause. MySQL comparison operators Mar 20, 2010 · I wonder if is it possible to run mysql command which can select an alternative field if the first given field is empty, on the same table. Nov 7, 2013 · The following query runs fine, but I want to input the option that if the email returned is NULL, then I input "[email protected]" or something similar. NULLs are sorted before the empty strings. file_name != '' and v. empty string issue is a Apr 16, 2016 · I've a mysql query to merge two tables on primary key IMO. I have tried if it is empty or NULL but the code below returns 0. – Feb 22, 2016 · Use inline IF to check for null and empty strings and if exists then return '0000'. An empty string "" is a blank string with the length of 0. 7. Different meanings, you see. `current_date` ='23/1/2018' AND loading_buses. Is there any way to get around it? Edit: this is just a simple example Aug 18, 2016 · Stack Overflow for Teams Where developers & technologists share private knowledge with coworkers; Advertising Reach devs & technologists worldwide about your product, service or employer brand; Knowledge Solutions Data licensing offering for businesses to build and improve AI tools and models; Labs The future of collective knowledge sharing Jan 6, 2022 · Using MySQL (MariaDB) I'm looking to see if a sub-query returns null, if so I want it to be 0. So in short words, On duplicate key . The table i want to query looks like this: Jan 12, 2019 · Stack Overflow for Teams Where developers & technologists share private knowledge with coworkers; Advertising Reach devs & technologists worldwide about your product, service or employer brand; Knowledge Solutions Data licensing offering for businesses to build and improve AI tools and models; Labs The future of collective knowledge sharing Jun 22, 2013 · SELECT COALESCE(Field1,NULL) AS Field1 FROM Table1. The use of one or two bytes for storing NULL applies only to InnoDB REDUNDANT row format. Dec 3, 2009 · If you want a ‘don't know’ placeholder use a NULL; if you simply want to store an empty string that behaves like an empty string, go ahead and store an empty string. Dec 6, 2016 · I am trying to figure out how to check if a field is NULL or empty. Dec 8, 2015 · Given 2 tables tbl1 and tbl2. When i edit a data in Table A, it needs to check if the same data is present in Table B, If data is present in Table B, just ignore updation, if data is empty or Null, t Apr 6, 2016 · Do not do this if you don't need the additional state. Asking for help, clarification, or responding to other answers. If all arguemnts are null, it'll return null, but we're forcing an empty string there, so no null values will be returned. Some more differences: A LENGTH of NULL is NULL, a LENGTH of an empty string is 0. SELECT IF(customer_id='' OR customer_id IS NULL,'0000',customer_id) FROM customer c LEFT JOIN user u ON u. Why would you want to store something (empty string) if there is no value? Better use null which indicates exactly that - no value. Feb 2, 2024 · Explicitly some keywords like IS NULL get used along with column names to filter out null values. time_out is null then '' else sa. I have a int() column that could be either: NULL, 0 or EMPTY. The use of the LENGTH function to return NULL, which gracefully handles the situation where an empty string is present. NULL can't be 49080, 49078, 49284 or any other number or string. Provide details and share your research! But avoid …. So I expected NULL to appear in the entire column. I currently have a test for NULL which works fine (part of a MySQL SELECT statement / stored procedure). ) Try inserting null into the primary key for the varchar. As @David says above, the empty string cannot be converted to an int, and so MySQL chooses null instead. Representing the same thing in two different ways is a bad idea. pzzms ejvd udwsa yagpv goyxfi nhgqf tlrlg ugqaw xvmwd rkxr