EntityFrameWork Update Multiple Rows
Batch update/delete EF5
I have a simple question about calculating distances in PostGIS.  I would like to get the distance between two geometries. I am using this sid : 4269 in meters what i am doing now is this : ST_Distance((a.geom,b.geom)) FROM ... but I am getting result in degrees. I think that I should work with geography but how can I cast a geom to a geography? I tried with (a.geom::geography) but i am getting an error.  What can I do to get my result in meters?   Thank You What is LookDev/Material Preview mode for in 2.8? What is the use of the square brackets [] in sql statements? Why ZSH ends a line with a highlighted percent symbol? I've noticed this on occasion with a variety of applications. I've often thought it was because the output was cancelled early (ctrl+c, for example) or something similar, and zsh is filling in a new line character. But now curiosity has gotten the best of me, since it doesn't seem to do this in bash.   zsh    bash    The Sequence program is something I pulled from a book while reading on Java certifications and just wanted to see if it would compile and run. I did notice that it does not use the println() method from the System.out package/class. Instead it uses plain old print().  Is the lack of a new line character the reason I get this symbol? How do I show for an ideal transformer $M^2=L_1L_2$? I've been stuck on this problem for about an hour.     In an ideal transformer, the same flux passes through all turns of the primary and of the secondary . Show that in this case $M^2=L_1L_2$, where $M$ is the mutual inductance of the coils, and $L_1$, $L_2$ are their individual self-inductances.   My first instinct was the following: If we isolate the response of each coil to the other one, we get the equations $N_1\Phi_1=MI_2$ and $N_2\Phi_2=MI_1$, where $\Phi$ is magnetic flux going through a single turn of the coil and $I$ is current. Likewise, if we isolate the response of each coil to itself, we get the equations $N_1\Phi_1=L_1I_1$ and $N_2\Phi_2=L_2I_2$. I would now naturally want to say "Now just multiply $N_1\Phi_1$ and $N_2\Phi_2$ both ways, and get the desired result!" i.e.,  $$(N_1\Phi_1)(N_2\Phi_2)=(MI_2)(MI_1)=(L_1I_1)(L_2I_2)\implies M^2=L_1L_2$$  But that's incorrect, because the response of the coils to themselves and to the other coil are different quantities (i.e. not necessarily equal).  Realizing this, I write down the more general equations.  $$N_1\Phi_1=MI_2+L_1I_1$$ $$N_2\Phi_2=MI_1+L_2I_2$$  Now even with the hypothesis that $\Phi_1=\Phi_2=\Phi$, I still can't see how the identity $M^2=L_1L_2$ follows. Could you help clear up my confusion?  *Taken from D. Griffiths Introduction to Electrodynamics (4th ed.), Problem 7.58. Prove that $ m_{a} \geq m_{g} \geq m_{h} $ using strict inequalities unless $ a = b $. $ m_{a} = \frac{1}{2} (a + b) $   $ m_{g} =  \sqrt{ab} $   $ \frac{1}{m_{h}} = \frac{1}{2}(\frac{1}{a} + \frac{1}{b})$   Attempted Solution:  I believe I have shown the first step, which is $ m_{a} \geq m_{g} $ but i'm stuck on showing $ m_{g} \geq m_{h} $  $ \frac{a + b}{2} &gt; \sqrt{ab} $  $ (\frac{a + b}{2})^2 &gt; (\sqrt{ab})^2 $  $\frac{a^2 + 2ab + b^2}{4} &gt; ab$  $a^2 + 2ab + b^2 &gt; 4ab $  $a^2 -2ab + b^2 &gt; 0 $  $(a - b)^2 &gt; 0 $   so if $a = b$ we have $(a -b)^2 \geq 0$  Therefore, $m_{a} \geq m_{g} $  Now, i'm not sure if that is correct or not, if not can you please guide me to the complete solution or if I am correct on this part, provide a solution for $m_{g} \geq m_{h} $ Why has a circle when the point light through my glass？ I found there is a circle when the point light through my glass material using the circle render.  How could I solve it? If a sequence $(u_n)$ be such that its every subsequence has a subsequence that converges to $0$, then $\lim u_n= 0$ Tracking down where disk space has gone on Linux? Is there an English term for "L'esprit de l'escalier"? How can I give a script its own icon in the Unity launcher? With Ubuntu 16.04, if you create a launcher (desktop file in ~/.local/share/applications) with a custom icon for a terminal application (so with Terminal=true) then when you start it, it will spawn a new standard terminal icon, and your custom icon will pulse and disappear within a few seconds.  In 14.04, it just worked as expected. (it would not start a new standard terminal icon).   Any idea what to do to change this behaviour? I have a few terminal apps that I want to launch from unity and the new behaviour is problematic (I lose trace of which is which since they all end up with the standard terminal icon)... Migrating from Evolution to Thunderbird Automatically update field value in one column based on change to another column in same table? When editing I want to be able to change the attributes of one field and upon doing this allow for the automatic update of another field in the same attribute table.   Essentially I have one layer with a code, description and legend information.   I would like to be able to edit the code and have the description and the legend information update with this edit with its correct description and legend information.   Is there any way to do this within ArcMap's tools or an associated script? How to show $A\times (B\cup C) = (A\times B)\cup (A\times C)$ For example Lets use the Marrutact from Sandstorm, it can cast as a 5th level wizard. if it then takes a prestige class that requires the ability to cast 1st level Arcane spells and advances arcane casting such as Abjurant Champion. assuming it meets all other prerequisites does the Marrutacts spellcasting improve when it takes a level in Abjurant Champion or does it gain no benefit? Why is accuracy not the best measure for assessing classification models? Can we have threaded comments? The conversation often continues in the Comments and important information is held in the comments. I'd like to have threaded comments there. How can I repair the Windows 8 EFI Bootloader? Requesting review of technically inaccurate answers Some answers are plain wrong, or even harmful. Usually these get spotted pretty quickly and either fixed or deleted by the poster, on the basis of comments/votes.  Sometimes though these slip under the radar - the OP ignores the downvotes/comments, or nobody even picks up on it the first time around.  I've always assumed that VLQ flags in the 10K queue for answers that are technically flawed, but otherwise OK were effectively "request for review by somebody knowledgeable in this area". It seems though that .  How should answers like this be handled instead if VLQ is not appropriate? Is there a mechanism for requesting further review? Raising them in chat is sometimes an option, but not always appropriate.   The useful actions that might happen as a result of increased visibility:   Edits by domain experts Downvotes to hide the poor answer Less flawed answers by experts Delete votes by 20K users   Would a "technical issue flag" that pushes to a tab in  /review help? How to run my own program without specifying its path Let's suppose I have compiled something and I run it like so:  $ /path/to/my/executable/mycmd Hello World   What do I need to do to run it like   $ mycmd Hello World    from everywhere in my computer?