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MySQL DISTINCT on a GROUP_CONCAT()
I am doing SELECT GROUP_CONCAT(categories SEPARATOR ' ') FROM table . Sample data below:
6 Answers
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Join vs. sub-query
...and query-specific.
Historically, explicit joins usually win, hence the established wisdom that joins are better, but optimisers are getting better all the time, and so I prefer to write queries first in a logically coherent way, and then restructure if performance constraints warrant this.
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Sqlite: CURRENT_TIMESTAMP is in GMT, not the timezone of the machine
I have a sqlite (v3) table with this column definition:
11 Answers
11
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Alternate output format for psql
I am using PostgreSQL 8.4 on Ubuntu. I have a table with columns c1 through cN . The columns are wide enough that selecting all columns causes a row of query results to wrap multiple times. Consequently, the output is hard to read.
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UITableView backgroundColor always gray on iPad
When I set the backgroundColor for my UITableView it works fine on iPhone (device and simulator) but NOT on the iPad simulator. Instead I get a light gray background for any color I set including groupTableViewBackgroundColor .
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How to align center the text in html table row?
I am using an HTML <table> and I want to align the text of <td> to the center in each cell.
7 Answers
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Creation timestamp and last update timestamp with Hibernate and MySQL
...ons, you can use @PrePersist and @PreUpdate event hooks do this:
@Entity
@Table(name = "entities")
public class Entity {
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private Date created;
private Date updated;
@PrePersist
protected void onCreate() {
created = new Date();
}
@PreUpdate
protected void onUpdate() {
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Find intersection of two nested lists?
...but because set membership is in average O(1) (for example when using hash table), it is big difference,for example because amortized time is guaranteed.
– miroB
Dec 4 '17 at 20:27
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How to write a JSON file in C#?
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@RobertHarvey Liam's Json.Net link has a nice table showing what the differences are. Coming from the people that make it, of course you should take it with a grain of salt, but it is indeed better than the built-in things.
– Tim S.
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UITableview: How to Disable Selection for Some Rows but Not Others
I am displaying in a group tableview contents parsed from XML. I want to disable the click event on it (I should not be able to click it at all) The table contains two groups. I want to disable selection for the first group only but not the second group. Clicking the first row of second group nav...