![]() ![]() Now, the row.column_name works as expected and we can help users pick the column(s) they want to sync to their tools. I don't feel like this should be necessary, but you can't argue with (database) results. The code now does this query: mysql> SELECT column_name AS column_name FROM INFORMATION_SCHEMA.COLUMNS ![]() The solution that I came up in the pull request was to be more explicit. Having seen this, I was lacking the confidence to assume it was either way. Our code with row.column_name failed because it was undefined. We had only encountered lowercase values returned, but then ran across this one with a new user. Each subclause provides a subquery that produces a result set, and associates a name with the subquery. I previously believed it was the same as all other tables in all respects. To specify common table expressions, use a WITH clause that has one or more comma-separated subclauses. I have not been able to figure what is going on other than to assume the INFORMATION_SCHEMA is just different. > WHERE table_schema = 'db' AND table_name = 'users' ĭo you see what has happened here? I asked for lowercase column_name like before, but I got back uppercase COLUMN_NAME. We do a query that looks something like this: mysql> SELECT column_name FROM INFORMATION_SCHEMA.COLUMNS In this process, we have to introspect the database. Our tool, Grouparoo connects to sources like MySQL to learn about customers and sync that data to destinations like Salesforce. So you have to be a little careful here, but often, the same code is doing the query and using it. However, if the uppercase query was used ( SELECT FIRST_NAME FROM USERS) instead, it would output The user is: undefined. This would output The user is: John as expected. query ( "SELECT first_name FROM users", function ( error, results, fields ) ) So let's say I had code like this: connection. Notice that the data is the same, but the "header" is different in each case. I believed this to be true even about identifiers like columns names.įor example, both of these queries returns the same data even though the "real" column is defined in lowercase. ![]() This debate is made possible by the fact that, generally, it does not matter. Here c_name is the column name storing the status of the record, checked or not.ĭownload the SQL dump of the above student table Example By using SQL CASE we can get records based on Financial Year wise.There is a debate among a very specific set of people about what case to use in SQL queries. SELECT CASE WHEN c_name IS NOT NULL THEN 'checked' If any column has NULL data and we want to return 'checked' when it is not null and return 'not_checked' when it is NULL. ![]() Sum(CASE WHEN gender ='Female' THEN 1 ELSE 0 END) as Female Sum(CASE WHEN gender ='male' THEN 1 ELSE 0 END) as Male, We can further break the gender column to get number of male and female in each class by using SQL GROUP BY. While grouping in a rang it is better to use MySQL BETWEEN Query SELECT `id`, `name`, `class`, `mark`, `gender` , Here student grade is awarded based on the mark they got. Here we check the condition and if it is True then the respective statement is executed. In this case we don't specify any value or data to be matched, instead we work on testing some conditions and if it is True then respective statement is to be executed. We can display based on the floor wise or location wise by using order by query SELECT `id`, `name`, `class`, `mark`, `gender` ,įROM `student` ORDER BY location Second Type (Matching condition with CASE statement) There are more records, here it is limited to 10 only. SELECT `id`, `name`, `class`, `mark`, `gender` , Using CASE in our query statement is here. Our list should display student details with class and location of the class. If a searchcondition evaluates to true, the corresponding SQL statement list. We have allotted rooms for the classes at different floors in a school. The CASE statement for stored programs implements a complex conditional construct. We will use our student table for this example. If any WHEN statement is matched then rest WHEN statements are not checked and matched statement is returned. If nothing is matched then statement under X_statement is executed. If it is not matched than next WHEN value C_value is checked. If A_value equals to B_value then B_statement is executed. Here A_value is matched with different values given under WHEN. this means that if id<800, success has to be 1 for the condition to be evaluated as true. MySQL case – when –then to match against value or condition with GROUP by and BETWEEN query You don't have to use CASE.WHEN, you could use an OR condition, like this: WHERE pw'correct' AND (id>800 OR success1) AND YEAR (timestamp)2011. ![]()
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