![]() SELECT CONCAT( 'MySQL', 'CONCAT') Code language: SQL (Structured Query Language) ( sql ) The following statement concatenates two quoted strings: MySQL and CONCAT. If any argument is NULL, the CONCAT function returns a NULL value. The CONCAT function converts all arguments to the string type before concatenating. ) Code language: SQL (Structured Query Language) ( sql ) The following illustrates the syntax of the CONCAT function. The CONCAT function requires a minimum of one parameter otherwise it raises an error. The MySQL CONCAT function takes one or more string arguments and concatenates them into a single string. In Microsoft SQL server, you use the addition arithmetic operator (+) to concatenate string values.īesides using spaces for string concatenation, MySQL provides two other functions that concatenate string values: CONCAT and CONCAT_WS. For example, if you use PostgreSQL or Oracle, you have to use the string concatenation operator ||. MySQL string concatenation is cleaner in comparison with other database management systems. To concatenate two or more quoted string values, you place the string next to each other as the following syntax: SELECT 'MySQL ' 'String ' 'Concatenation' Code language: SQL (Structured Query Language) ( sql ) However, since this example is rather contrived, this shouldn't be an issue for "genuine" strings where the normal ASCII sort order should be acceptable.Ĭleaned up (extraneous fields removed) version - same result.Summary: in this tutorial, you will learn various ways to concatenate two or more strings together by using the MySQL CONCAT and CONCAT_WS functions. 9, 10, 11 - it appears as 10, 11, 9 - which is the individual csv strings sorted ASCII wise, not numerically. Unfortunately, there is no way of sorting the strings internally by record - i.e. To have the first group of 2 contain 9, 10 & 11, the rn is necessary. In order to get the first 3 strings into the first slot per id, we have to keep the rn field down through the SQL - for example, group 2 has 9, 10, 11 & 12. ROW_NUMBER() OVER (PARTITION BY id, cal_1 ORDER BY id, rn1) AS cal_2 ![]() So, we now have our csv strings in groups of 3, by virtue of their id field and the cal_2 field which allows us to do use SQLite's GROUP_CONCAT() built-in aggregate function as follows (I found this post helpful): SELECT ROW_NUMBER() OVER (PARTITION BY id, cal_1 ORDER BY id, csv) AS cal_2 Now, we have to obtain a handle on our groups of threes - putting each group of three into a separate group. The field that interests us is cal_1, which starts at 0 and cycles through 1 & 2 and then goes back to 0 - from the beginning! ![]() So, we can that rn1 % 3 isn't very helpful - it starts 1, 2 and then drops back to 0. The next step is to start the grouping of the csvs by threes. Id, csv, ROW_NUMBER() OVER (PARTITION BY id ORDER BY id) AS rn1ġ 1 1 <<- csv is a string (TEXT), rn is an INTEGER! Note also that the individual csvs are strings (TEXT) and do not represent numbers (this saved on typing.). The key here is to get the csvs into groups of 3 - therefore the modulus operator ( %) is the obvious choice, but even with that, there's still a bit of work to be done. Populated it (with extra data for testing): INSERT INTO csvs (id, csv) VALUES In order to answer this question, I did the following (all of the code below is available on the fiddle here): CREATE TABLE IF NOT EXISTS csvs ![]()
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